tag:theconversation.com,2011:/us/topics/oysters-2104/articlesOysters – The Conversation2023-12-13T03:28:22Ztag:theconversation.com,2011:article/2193952023-12-13T03:28:22Z2023-12-13T03:28:22ZPesticide residue from farms and towns is ending up in fresh oysters<figure><img src="https://images.theconversation.com/files/564439/original/file-20231208-27-22yb4u.jpeg?ixlib=rb-1.1.0&rect=11%2C11%2C1930%2C1444&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Author supplied</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>For years, oysters have been lauded as one of the most sustainable and healthy seafood options. But our food is only as healthy as the environment it is grown in. </p>
<p>In new research published in <a href="https://doi.org/10.1016/j.envpol.2023.123084">Environmental Pollution</a>, we found something unfortunate. These filter-feeding shellfish eat by straining particles from water. This, alas, makes them very good at soaking up pesticide residue. </p>
<p>When we analysed oysters growing naturally in the Richmond River estuary in New South Wales, we found 21 different pesticides – more than in the water. Each oyster had detectable amounts of nine different pesticides, on average. </p>
<p>We don’t know the full health risks of eating oysters from this river. But we do know five pesticides we found are potentially dangerous – they are not allowed to be present in meat due to the risks. </p>
<p>To be clear: the risk is largely in taking oysters from the wild. Commercially farmed oysters are likely to be safer, as they are regulated by Australia’s <a href="https://www.agriculture.gov.au/biosecurity-trade/export/controlled-goods/fish/registered-establishment/shellfish-qa">shellfish quality assurance program</a> and can only be harvested when water quality is good. </p>
<h2>How do pesticides get into oysters?</h2>
<p>Oysters pump water through their bodies and eat the bacteria, plankton and other particles they filter out. A single oyster can filter up to five litres of water an hour and over 250,000 litres in their lifetime. </p>
<p>Before colonisation, oyster reefs were everywhere. Most of these reefs were pulled out to use the shells for lime and the meat to eat. In the Richmond River, poor water quality and a disease killed off most oysters until a new, <a href="https://ozfish.org.au/2020/04/new-oyster-variety-potential-game-changer/">disease-resistant strain emerged</a>. </p>
<p>Filter-feeding works well if you’re just filtering out what’s found naturally. But if the water is contaminated, oysters can end up storing pathogens and pollutants in their bodies. </p>
<p>Oysters prefer brackish water – where fresh meets salt. That’s why they’re intensively farmed in many estuaries. But because many of our coastal catchments now contain farms, towns or cities, the pesticides, herbicides and insecticides we use wash into rivers after rain.</p>
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<a href="https://images.theconversation.com/files/564436/original/file-20231208-21-22yb4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="oysters on a rock" src="https://images.theconversation.com/files/564436/original/file-20231208-21-22yb4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/564436/original/file-20231208-21-22yb4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564436/original/file-20231208-21-22yb4u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564436/original/file-20231208-21-22yb4u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564436/original/file-20231208-21-22yb4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564436/original/file-20231208-21-22yb4u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564436/original/file-20231208-21-22yb4u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Sydney rock oysters have a remarkable ability to filter water but can also accumulate pesticides in the process.</span>
<span class="attribution"><span class="source">Kirsten Benkendorff</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<h2>What did we find in these oysters?</h2>
<p>Most of the herbicides, insecticides and fungicides we found are used routinely by farmers, land managers and council workers. </p>
<p>But we did find an unwelcome surprise – the fungicide benomyl, which has been illegal in Australia since 2006 due to the high risk to human health and the environment. Detecting this chemical means someone is using it illegally. </p>
<p>Four pesticides – atrazine, diuron, hexazinone and metolachlor – were found in concentrations above safe environmental limits for <a href="https://www.waterquality.gov.au/anz-guidelines/guideline-values/default/water-quality-toxicants/search">fresh and marine water</a>.</p>
<p>Atrazine and diuron are among the most commonly used herbicides in Australian farming, but they are not safe chemicals. They’re known to contaminate groundwater and surface water, and have been detected in unsafe levels in the <a href="https://doi.org/10.1016/j.envpol.2009.03.006">waters of the Great Barrier Reef</a>. </p>
<p>Atrazine is banned in the European Union over concerns about the damage it can do to the environment and the risk of it getting into drinking water. </p>
<p>Diuron has been <a href="https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A32023R1656">severely restricted</a> in the EU, but is commonly used by the sugarcane industry in Australia. Like atrazine, diuron can pollute groundwater and kill aquatic species, and is <a href="https://pubmed.ncbi.nlm.nih.gov/26086120/">carcinogenic to humans</a>. </p>
<p>Australia’s pesticide authority suspended the use of 63 diuron products <a href="https://www.apvma.gov.au/sites/default/files/publication/15396-diuron-review-report.pdf">in 2011</a>. The ban only lasted a year, following <a href="https://search.informit.org/doi/abs/10.3316/ielapa.336804883887109">lobbying from sugarcane growers</a>, and diuron is back in use. </p>
<h2>What does this mean for oyster eaters?</h2>
<p>The sheer number of different pesticides we found in oysters was perhaps the biggest concern for lovers of oysters. Five of these – pebulate, vernolate, fosetyl Al, benomyl and prothiofos – have residue limits set at zero for meat. That is, if you want to sell meat, it cannot have any detectable level of these pesticides. (At present, our food safety guidelines have no specific limits for most pesticides in seafood.)</p>
<p>What about the 16 other pesticides we found? Most were below the allowable residue limits in meat on their own, but we have very little understanding of the combined effects of exposure from multiple pesticides. </p>
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Read more:
<a href="https://theconversation.com/the-real-cost-of-pesticides-in-australias-food-boom-20757">The real cost of pesticides in Australia's food boom</a>
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<a href="https://images.theconversation.com/files/564446/original/file-20231208-29-za277f.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="rock oyster on dock" src="https://images.theconversation.com/files/564446/original/file-20231208-29-za277f.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/564446/original/file-20231208-29-za277f.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564446/original/file-20231208-29-za277f.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564446/original/file-20231208-29-za277f.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564446/original/file-20231208-29-za277f.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564446/original/file-20231208-29-za277f.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564446/original/file-20231208-29-za277f.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">These Sydney rock oysters have come from an oyster lease in the Richmond River.</span>
<span class="attribution"><span class="source">Kirsten Benkendorff</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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</figure>
<h2>What should be done?</h2>
<p>The problem for oyster farmers and marine managers is they’re effectively powerless to prevent water pollution entering the river from farms or towns upstream. </p>
<p>The first step is to find out how bad the problem is. We need dedicated pesticide monitoring programs for seafood producers in estuaries to gauge the size of the problem and look for hotspots. </p>
<p>If hotspots are found, the next step is to work with farmers and land managers to collaboratively design solutions. </p>
<p>These could include incentives to cut pesticide use through <a href="https://www.epa.nsw.gov.au/your-environment/pesticides/integrated-pest-management">integrated pest management</a> and <a href="https://www.csiro.au/en/research/plants/crops/farming-systems/precision-agriculture">precision agriculture</a> as well as the use of tools to decide <a href="https://link.springer.com/article/10.1007/s11356-023-29814-w">which pesticide to use and when</a>. </p>
<p>Strategically located wetlands and <a href="https://www.youtube.com/watch?v=G8wIJ8hVYlc&t=6s">bacterial bioreactors</a> able to break down pesticides can also stop these chemicals arriving in the river. </p>
<p>Mangrove and shellfish reef restoration could help protect commercial oyster farms and other seafood harvesting areas. Like oysters, mangroves have the ability to remove chemical contaminants from the water and store them internally. </p>
<p>You might be wondering why some of these chemicals are legal to use in the first place. It’s very time consuming to seek review of currently available pesticides in Australia. Scientists or community members have to demonstrate these products cause harm, even if they have been reviewed and banned in many other nations. </p>
<h2>Can I still eat oysters?</h2>
<p>Yes. To cut your personal risk, buy only from reputable commercial oyster farms. These farms are only allowed to harvest oysters when the water quality is good, which helps remove water soluble pesticides. Given most of us don’t eat oysters daily, the risk is likely to be low. </p>
<p>What you should avoid is harvesting your own oysters in estuaries where there are farms or towns upstream. These may have accumulated pesticides. Leave them where they are – they’re doing a very important job: cleaning the water. </p>
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Read more:
<a href="https://theconversation.com/once-the-fish-factories-and-kidneys-of-colder-seas-australias-decimated-shellfish-reefs-are-coming-back-184063">Once the fish factories and ‘kidneys’ of colder seas, Australia’s decimated shellfish reefs are coming back</a>
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<p class="fine-print"><em><span>Kirsten Benkendorff receives funding from the NSW Government for other current projects on seafood and water quality.</span></em></p><p class="fine-print"><em><span><a href="mailto:amanda.reichelt-brushett@scu.edu.au">amanda.reichelt-brushett@scu.edu.au</a> receives funding from the NSW State Government. She is affiliated with the Richmond RiverKeeper Association. </span></em></p><p class="fine-print"><em><span><a href="mailto:e.jamal.10@student.scu.edu.au">e.jamal.10@student.scu.edu.au</a> receives funding from the Australia Awards Scholarship and postgraduate funding from the Faculty of Science, Southern Cross University.</span></em></p>Herbicides and pesticides wash downriver from farms and towns – and some of these chemicals are taken up by oysters.Kirsten Benkendorff, Professor, Southern Cross UniversityAmanda Reichelt-Brushett, Professor Environmental and Marine Science, Southern Cross UniversityEndang Jamal, Senior lecturer in aquaculture, Pattimura University and doctoral student, Southern Cross UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1985732023-01-26T17:01:47Z2023-01-26T17:01:47ZBeavers and oysters are helping restore lost ecosystems with their engineering skills – podcast<figure><img src="https://images.theconversation.com/files/506490/original/file-20230125-26-149wf3.jpg?ixlib=rb-1.1.0&rect=0%2C417%2C2216%2C1528&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Beavers dramatically change a landscape by building dams that create ponds of still water.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Castor_fiber_04(js),_Narew_River,_Poland.jpg#/media/File:Castor_fiber_04(js),_Narew_River,_Poland.jpg">Jerzy Strzelecki/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Whether you are looking at <a href="https://theconversation.com/ending-amazon-deforestation-4-essential-reads-about-the-future-of-the-worlds-largest-rainforest-194800">tropical forests in Brazil</a>, <a href="https://news.stanford.edu/2019/01/15/save-native-grasslands-study-invasive-species/">grasslands in California</a> or <a href="https://theconversation.com/we-all-know-the-great-barrier-reef-is-in-danger-the-un-has-just-confirmed-it-again-195551">coral reefs in Australia</a>, it is hard to find places where humanity hasn’t left a mark. The scale of the alteration, invasion or destruction of natural ecosystems can be mindbogglingly huge.</p>
<p>Thankfully, researchers, governments and everyday people around the world are putting more effort and money into conservation and restoration every year. But the task is large. How do you plant a billion trees? How do you restore thousands of square miles of wetlands? How do you turn a barren ocean floor back into a thriving reef? In some cases, the answer lies with certain plants or animals – called ecosystem engineers – that can kick-start the healing. </p>
<p>In this episode of “<a href="https://theconversation.com/uk/topics/the-conversation-weekly-98901">The Conversation Weekly</a>,” we talk to three experts about how ecosystem engineers can play a key role in restoring natural places and why the human and social sides of restoration are just as important as the science.</p>
<iframe src="https://embed.acast.com/60087127b9687759d637bade/63d27eb5cd0f7200118faf4b" frameborder="0" width="100%" height="190px"></iframe>
<p><iframe id="tc-infographic-561" class="tc-infographic" height="100" src="https://cdn.theconversation.com/infographics/561/4fbbd099d631750693d02bac632430b71b37cd5f/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Ecosystem engineers are plants or animals that create, modify or maintain habitats. As <a href="https://www.birmingham.ac.uk/staff/profiles/gees/larsen-joshua.aspx">Joshua Larsen</a>, an associate professor at the University of Birmingham, explains, beavers are a perfect example of an ecosystem engineer because of the dams and ponds they build.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/506498/original/file-20230125-2999-qvqftz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A strip of green surrounding ponds in a burned landscape." src="https://images.theconversation.com/files/506498/original/file-20230125-2999-qvqftz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506498/original/file-20230125-2999-qvqftz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=451&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506498/original/file-20230125-2999-qvqftz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=451&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506498/original/file-20230125-2999-qvqftz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=451&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506498/original/file-20230125-2999-qvqftz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506498/original/file-20230125-2999-qvqftz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506498/original/file-20230125-2999-qvqftz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Beaver ponds can create valuable wetland habitats that store water and support life.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Beaver_ponds_and_wetlands_in_Baugh_Creek,_Idaho,_act_as_a_wildfire_%22emerald_refuge%22_September_6,_2018.png#/media/File:Beaver_ponds_and_wetlands_in_Baugh_Creek,_Idaho,_act_as_a_wildfire_%22emerald_refuge%22_September_6,_2018.png">Schmiebel/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>“They create this pocket of still water, which allows aquatic vegetation to start to colonize that wouldn’t otherwise be there,” says Larsen. Once a beaver establishes a pond, the surrounding area begins to change from a creek or river into a wetland.</p>
<p>Larsen is part of an <a href="https://theconversation.com/beavers-are-back-heres-what-this-might-mean-for-the-uks-wild-spaces-166912">effort to reintroduce beavers into Britain</a>, a place where they have been extinct for over 500 years and the landscape reflects that loss. There used to be hundreds of thousands of beavers – and hundreds of thousands of beaver ponds – all across Britain. Without beavers, it would be prohibitively difficult to restore wetlands at that scale. But, as Larsen explains, “Beavers are doing this engineering of the landscape for free. And more importantly, they’re doing the maintenance for free.”</p>
<p>This idea of using ecosystem engineers to do the labor-intensive work of restoration for free is not limited to beavers. Dominic McAfee is a researcher at the University of Adelaide in Australia. He studies oysters and is leading a project to <a href="https://theconversation.com/huge-restored-reef-aims-to-bring-south-australias-oysters-back-from-the-brink-77405">restore oyster reefs</a> on the eastern and southern coasts of Australia.</p>
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<a href="https://images.theconversation.com/files/506499/original/file-20230125-18-rvcct8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large group of thousands of oysters emerging from water." src="https://images.theconversation.com/files/506499/original/file-20230125-18-rvcct8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506499/original/file-20230125-18-rvcct8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506499/original/file-20230125-18-rvcct8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506499/original/file-20230125-18-rvcct8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506499/original/file-20230125-18-rvcct8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506499/original/file-20230125-18-rvcct8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506499/original/file-20230125-18-rvcct8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Oyster reefs provide important structure that supports entire ecosystems.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Oyster_reef_Hunting_Island_SC.jpg#/media/File:Oyster_reef_Hunting_Island_SC.jpg">Jstuby/Wikimedia Commons</a></span>
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<p>“These reefs were the primary sort of marine habitat in coasts, coastal bays and estuaries over about 7,000 kilometers (4,350 miles) of Australian coastline,” says McAfee. But today, “They’re all gone. All those reefs were scraped from the seafloor over the last 200 years.” </p>
<p>When you lose the oysters, you lose the entire reef ecosystem they support. So, a few years ago, McAfee and his colleagues decided to start bringing these reefs back. Oysters need a hard surface – like a rock, or historically, other oysters – to grow on. But all those old oyster reefs are gone and only sand remains. “So the first step to restore oysters is to provide those hard foundations. We’ve been doing that in South Australia by deploying limestone boulders,” explains McAfee. After just a year, McAfee and his colleagues are starting to see results, with millions of oyster larva sticking to these boulders. </p>
<p>At this point, McAfee says that challenges are less about the science and more about getting community and political support. And that is where <a href="https://www.uidaho.edu/caa/programs/landscape-architecture/our-people/andrew-kilskey">Andrew Kliskey</a> comes in. Kliskey is a professor of community and landscape resilience at the University of Idaho in the U.S. He approaches restoration and conservation projects by looking at what are called social-ecological systems. As Kliskey explains, “That means looking at environmental issues not just from a single disciplinary point of view, but thinking that many things are often occurring in a town and in a community. Really, social-ecological systems means thinking about people and the landscape as being intertwined and how one interacts with the other.” </p>
<p>For scientists, this type of approach involves sociology, economics, indigenous knowledge and listening to communities that they are working with. Kliskey explains that it’s not always easy: “Doing this sort transdisciplinary work means being prepared to be uncomfortable. Maybe you’re trained as a hydrologist and you have to work with an economist. Or you work in a university and you want to work with people in a community with very real issues, that speak a different language and who have very different cultural norms. That can be uncomfortable.” </p>
<p>Having done this work for years, Kliskey has found that building trust is critical to any project and that the communities have a lot to teach researchers. “If you’re a scientist, it doesn’t matter which community you work with, you have to be prepared to listen.”</p>
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<p>This episode was produced by Katie Flood and Daniel Merino, with sound design by Eloise Stevens. It was written by Katie Flood and Daniel Merino. Mend Mariwany is the show’s executive producer. Our theme music is by Neeta Sarl. </p>
<p>You can find us on Twitter <a href="https://twitter.com/TC_Audio">@TC_Audio</a>, on Instagram at <a href="https://www.instagram.com/theconversationdotcom/">theconversationdotcom</a> or <a href="mailto:podcast@theconversation.com">via email</a>. You can also sign up to The Conversation’s <a href="https://theconversation.com/newsletter">free daily email here</a>. A transcript of this episode will be available soon. </p>
<p>Listen to “The Conversation Weekly” via any of the apps listed above, download it directly via our <a href="https://feeds.acast.com/public/shows/60087127b9687759d637bade">RSS feed</a>, or find out <a href="https://theconversation.com/how-to-listen-to-the-conversations-podcasts-154131">how else to listen here</a>.</p><img src="https://counter.theconversation.com/content/198573/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dominic McAfee receives funding from the Australian Research Council.
Joshua Larsen receives funding from the Natural Environment Research Council (NERC), UK.
Andrew Kliskey receives funding from the National Science Foundation in the U.S.
</span></em></p><p class="fine-print"><em><span> </span></em></p>Restoring entire ecosystems is a difficult and expensive process. Thankfully, certain species, called ecosystem engineers, can make restoration easier. Gaining social and political support is critical too.Daniel Merino, Associate Science Editor & Co-Host of The Conversation Weekly Podcast, The ConversationNehal El-Hadi, Science + Technology Editor & Co-Host of The Conversation Weekly Podcast, The ConversationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1880062022-10-26T19:03:27Z2022-10-26T19:03:27ZPlaying sea soundscapes can summon thousands of baby oysters – and help regrow oyster reefs<figure><img src="https://images.theconversation.com/files/491554/original/file-20221025-15-kxu99p.JPG?ixlib=rb-1.1.0&rect=36%2C73%2C4867%2C3183&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Dominic McAfee</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Imagine you’re in a food court and spoilt for choice. How will you choose where to eat? It might be the look of the food, the smell, or even the chatter of satisfied customers. </p>
<p>Marine animals do the same thing when choosing a good place to live. Even seemingly simple creatures such as marine larvae use sight, smell and sound as navigational cues. Once we understand these cues, we can use them to help nature recover faster than it would on its own. </p>
<p>In our <a href="https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2664.14307">new research</a>, we amplified the natural sounds of the sea through underwater speakers. We were testing if sound cues would draw baby oysters to swim to the locations where we are trying to regrow oyster reefs. It worked better than we’d hoped. Many thousands more larvae swam to our locations than control areas and settled on the bare rocks. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/491532/original/file-20221025-15-ckrqgl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Flat oyster" src="https://images.theconversation.com/files/491532/original/file-20221025-15-ckrqgl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/491532/original/file-20221025-15-ckrqgl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491532/original/file-20221025-15-ckrqgl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491532/original/file-20221025-15-ckrqgl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491532/original/file-20221025-15-ckrqgl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491532/original/file-20221025-15-ckrqgl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491532/original/file-20221025-15-ckrqgl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Billions of Australian flat oysters once filtered our coastal seas. Could they return?</span>
<span class="attribution"><span class="source">John Turnbull/Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Why can’t these reefs return naturally?</h2>
<p>Oyster reef restoration is <a href="https://conbio.onlinelibrary.wiley.com/doi/10.1111/cobi.13958">gaining momentum</a> in Australia and globally as a way to restore healthy ecosystems. Reefs of shellfish filter and clean vast volumes of water as they feed, while their shell piles provide habitat for fish. Oysters are also food for many marine species. </p>
<p>These highly productive shellfish reefs once spanned thousands of kilometres of Australian waters, but more than 90% were dredged up for food and or to use their shells as lime for cement during the early colonial years.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-surprising-benefits-of-oysters-and-no-its-not-what-youre-thinking-90697">The surprising benefits of oysters (and no, it's not what you're thinking)</a>
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</em>
</p>
<hr>
<p>When we try to restore these reefs, however, we hit a problem. Free-swimming baby oysters need to find the boulders we drop onto sandy seafloors at our restoration sites. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/491538/original/file-20221025-11-8d2iyh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/491538/original/file-20221025-11-8d2iyh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/491538/original/file-20221025-11-8d2iyh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=344&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491538/original/file-20221025-11-8d2iyh.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=344&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491538/original/file-20221025-11-8d2iyh.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=344&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491538/original/file-20221025-11-8d2iyh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=432&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491538/original/file-20221025-11-8d2iyh.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=432&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491538/original/file-20221025-11-8d2iyh.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=432&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Restoring shellfish reefs starts with a limestone base, as in this construction image of the Glenelg oyster reef project.</span>
<span class="attribution"><span class="source">Maritime Constructions</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>That’s where our siren songs come in. Many marine animals use sound like we use sight on land. Think of whalesong, which lets whales communicate over long distances. Sound is more useful than sight or smell underwater because it can carry information a long way – much further than you can see – and without getting pushed about by ocean currents. </p>
<p>If you’ve snorkelled on a coral or rocky reef, you’ll know healthy reefs are surprisingly noisy. As you float over the reef, you hear a cacophony of sound: crackles and pops from fish as they feed and invertebrates like <a href="https://theconversation.com/baby-oysters-follow-the-crackling-sound-of-snapping-shrimp-182514">snapping shrimp</a>. </p>
<p>If this soundscape is present, it tells oyster larvae it’s a healthy habitat. And because sound travels so well, the soundscapes are broadcast a decent distance. That’s why it’s such a useful cue if you’re a baby oyster looking for a rock to settle on and begin growing your shell. </p>
<p>To test if this works outside the laboratory, we recorded sounds from the healthy Port Noarlunga Reef in South Australia. Then we played these sounds underwater near two large reef restoration sites offshore from Adelaide and the Yorke Peninsula. </p>
<p>This attracted up to 17,000 more oysters per square metre to our restoration sites. Not only that, but over the next five months, close to four times more large oysters grew in our test areas, which accelerated habitat growth. By contrast, the areas where we played ambient sound from oyster-free areas produced only stunted habitat with few oysters settling. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-worlds-most-degraded-marine-ecosystem-could-be-about-to-make-a-comeback-110233">The world's most degraded marine ecosystem could be about to make a comeback</a>
</strong>
</em>
</p>
<hr>
<h2>Hang on, oysters can hear?</h2>
<p>The way we hear is based on the pressure of soundwaves hitting our eardrums. Marine mammals like seals and dolphins hear this way too. But fish and marine invertebrates such as oysters are different. </p>
<p>Oyster larvae are brainless and earless, but they are certainly not clueless. Like fish, they hear by <a href="https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/2041-210X.12544">detecting and interpreting</a> the movement of water particles stirred up by soundwaves as they pass. Soundwaves alternately squish and stretch water particles, sending vibrations in the direction the <a href="https://dosits.org/decision-makers/tutorials/science/what-is-sound/">soundwave is moving</a>. Oysters sense this motion with tiny sensory hairs, or with statocysts, sensory organs used for balance and orientation. </p>
<p>Despite being only the width of a human hair themselves, larval oysters use these organs to follow these vibrations back towards the healthy reef producing the sound. In adult oysters, the tiny statocyst is near impossible to find. But swimming oyster larvae project their statocysts out in front of them, presumably to improve navigation and interpret marine sounds. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/491555/original/file-20221025-15-fm2yzw.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="oyster larvae" src="https://images.theconversation.com/files/491555/original/file-20221025-15-fm2yzw.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/491555/original/file-20221025-15-fm2yzw.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=448&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491555/original/file-20221025-15-fm2yzw.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=448&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491555/original/file-20221025-15-fm2yzw.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=448&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491555/original/file-20221025-15-fm2yzw.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=563&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491555/original/file-20221025-15-fm2yzw.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=563&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491555/original/file-20221025-15-fm2yzw.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=563&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">You can see the oyster larvae’s sound-sensing organ covered in tiny hairs.</span>
<span class="attribution"><span class="source">S. Pouvreau/Ifremer</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>The reefs are alive with the sound of music</h2>
<p>Researchers and community groups around the world are launching restoration efforts to repair some of the damage we’ve done. In Queensland, for instance, fishing communities in Moreton Bay offshore from Brisbane plan to restore 100 hectares of oyster reef <a href="https://ozfish.org.au/projects/moreton-bay-shellfish-reef-restoration/">over the next decade</a>.</p>
<p>While exciting, success isn’t guaranteed. It can be hard to restore ecosystems which haven’t existed for a century. And it can be expensive to get large stocks of larvae. </p>
<p>This technique – and others like it – could help improve how many baby oysters or other keystone species actually make it to their new homes and start the great task of reef-building. </p>
<p>Researchers have discovered fish can be attracted to <a href="https://www.nature.com/articles/s41467-019-13186-2?ftag=">coral reef sites</a> by playing healthy reef noises, and it has long been known that birds can be drawn to <a href="https://www.jstor.org/stable/1520987#metadata_info_tab_contents">specific nesting sites</a> by playing their social calls. </p>
<figure class="align-center ">
<img alt="oyster reef virginia" src="https://images.theconversation.com/files/491533/original/file-20221025-11-bzssus.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/491533/original/file-20221025-11-bzssus.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=411&fit=crop&dpr=1 600w, https://images.theconversation.com/files/491533/original/file-20221025-11-bzssus.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=411&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/491533/original/file-20221025-11-bzssus.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=411&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/491533/original/file-20221025-11-bzssus.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=516&fit=crop&dpr=1 754w, https://images.theconversation.com/files/491533/original/file-20221025-11-bzssus.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=516&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/491533/original/file-20221025-11-bzssus.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=516&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Oyster reef restorations are taking place in countries like America. This image shows surviving oyster reefs in Virginia.</span>
<span class="attribution"><span class="source">Aileen Devlin/Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In science, there’s no such thing as a silver bullet and there are potential downsides. It wouldn’t help if we drew all larval oysters to our sites at the expense of others – or if we attracted predators in large numbers. </p>
<p>But if we do this carefully, these techniques could help re-establish the invisible acoustic highways of the sea – and turn the deathly quiet of many coastal waters back into vibrant, noisy and healthy oyster reefs. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/once-the-fish-factories-and-kidneys-of-colder-seas-australias-decimated-shellfish-reefs-are-coming-back-184063">Once the fish factories and ‘kidneys’ of colder seas, Australia’s decimated shellfish reefs are coming back</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/188006/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dominic McAfee receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Sean Connell receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Brittany Williams and Lachlan McLeod do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>By playing the sounds of healthy reefs, we can draw oysters back to the barrens where their reefs once stood.Dominic McAfee, Postdoctoral researcher, marine ecology, University of AdelaideBrittany Williams, PhD Candidate, University of AdelaideLachlan McLeod, PhD Candidate, University of AdelaideSean Connell, Professor, Program Director of Stretton Institute, Program Director of Environment Insitute, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1643302022-01-19T05:52:03Z2022-01-19T05:52:03ZLeaf oysters: the unsung heroes of estuaries are disappearing, and we know almost nothing about them<figure><img src="https://images.theconversation.com/files/441435/original/file-20220119-23-ibcqig.jpg?ixlib=rb-1.1.0&rect=11%2C23%2C3982%2C2970&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Charlotte Jenkins </span>, <span class="license">Author provided</span></span></figcaption></figure><p><em><strong><a href="https://theconversation.com/au/topics/am-i-not-pretty-enough-106740">Am I not pretty enough?</a></strong> This article is part of The Conversation’s series introducing you to Australia’s unloved animals that need our help.</em></p>
<hr>
<p>Camouflaged by a layer of silty mud, most people probably wouldn’t notice the large flat oysters lurking beneath shallow water in Australia’s coastal estuaries. These are remarkable “leaf oysters”, and they can form reefs, produce mauve pearls, and reach the size of a dinner plate.</p>
<p>Of the 14 species of reef-forming oysters and mussels in Australia, leaf oysters (<em>Isognomon ephippium</em>) are the least well known. <a href="https://www.tandfonline.com/doi/full/10.1080/13235818.2020.1837054">Our review</a>, published last year, found only 30 publications globally that mention leaf oysters. Half of those were only incidental recordings.</p>
<p>This is a huge problem because there is <a href="https://academic.oup.com/bioscience/article/61/2/107/242615">widespread evidence</a> of significant declines in the number and condition of shellfish reefs. In Australia, 99% of shellfish reefs have been <a href="https://www.shellfishrestoration.org.au/the-problem/">described as</a> “functionally extinct”, meaning the habitat these reefs previously provided has now been lost. </p>
<p>This has led to serious efforts in shellfish reef <a href="https://www.natureaustralia.org.au/what-we-do/our-priorities/oceans/ocean-stories/oyster-reef-habitat/">restoration</a>. Leaf oysters are crucial members of these ecosystems, and we need substantially more information about them to ensure they’re not left out of these programs. Let’s delve into what we do know.</p>
<h2>Meet the leaf oyster</h2>
<p>Oysters are often associated with <a href="https://theconversation.com/buy-australian-oysters-and-farmed-barramundi-5-tips-to-make-your-feast-of-summer-seafood-sustainable-172954">summer feasts and intensive aquaculture</a>. While leaf oysters are edible, they have a large shell to meat ratio and so aren’t particularly attractive as a source of food for humans. </p>
<p>But like the iconic pearl oysters, leaf oysters are members of the Pteridine family of bivalve molluscs and have an inner nacre layer. This means they can produce pearls mainly mauve in colour, or sometimes purple, bronze, cream or silver.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1006&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1006&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441429/original/file-20220119-25-17uuyje.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1006&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Leaf oysters can be the size of a dinner plate.</span>
<span class="attribution"><span class="source">Kirsten Benkendorff</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Although not much is known about the life history of leaf oysters, we do know they reproduce by spawning. Thousands of eggs and sperm are released into the water and develop into swimming larvae after fertilisation. Only a fraction of these survive and settle onto the substrate, where they develop into juvenile oysters. </p>
<p>Like other reef-forming oysters such as the Sydney rock oyster and the Pacific oyster, leaf oyster larvae appear to be attracted to the shells of the adult oysters. They attach to the surface via “byssus” – a matt of strong hair-like threads. This enables shell clusters to form, which can develop into leaf oyster reefs.</p>
<p>Leaf oysters are ecosystem engineers. When they live in dense clumps, they support an entire ecosystem of fish and other invertebrates. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=423&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=423&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441430/original/file-20220119-25-1u5ysy4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=423&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Leaf oysters are crucial members of shellfish reef ecosystems.</span>
<span class="attribution"><span class="source">Kirsten Benkendorff</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The flat, plate-like shape of the leaf oysters provides a complex three-dimensional habitat, with many nooks and crannies for species to seek shelter from drying out at low tide, and to hide from predators at high tide. Their shells provide a hard surface for other invertebrates to attach to, and form biofilms grazed by snails and fish.</p>
<p>Our preliminary studies on leaf oyster beds have detected a high diversity of fish species. Using underwater videos, we recorded a number of important fishing species, including yellowfin bream, dusky flathead, sand whiting, sand mullet, leatherjacket and black spotted snapper. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=459&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=459&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=459&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=576&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=576&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441427/original/file-20220119-23-wxqbf5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=576&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A screenshot from our undersea survey videos.</span>
<span class="attribution"><span class="source">Kirsten Benkendorff</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Keeping estuaries clean</h2>
<p>Leaf oyster reefs are found on soft sediment in estuaries, on sand, mud and among mangroves, in tropical and subtropical regions around the world. In Australia, they’re found from Exmouth in Western Australia to the Macleay River on the mid-north coast of New South Wales. </p>
<p>We’ve also seen leaf oysters on artificial rock walls and in shallow water along the edge of small boat harbours. Some of these are likely to be remnant populations of larger clusters or reefs, but given they’re often partially buried, there’s little information available about their past distribution.</p>
<p>Like <a href="https://theconversation.com/the-surprising-benefits-of-oysters-and-no-its-not-what-youre-thinking-90697">other oyster reefs</a>, we expect leaf oysters play a significant role in maintaining water quality and nutrient cycling in estuaries. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-surprising-benefits-of-oysters-and-no-its-not-what-youre-thinking-90697">The surprising benefits of oysters (and no, it's not what you're thinking)</a>
</strong>
</em>
</p>
<hr>
<p>Coastal lakes and estuaries are a major repository of run-off from agriculture and urban development, leading to poor water quality. Shellfish reefs in healthy estuaries can buffer this effect by removing particles and bacteria from the water, and reducing dissolved nutrients and algal blooms.</p>
<p>As animals that eat food suspended in water, leaf oysters can filter vast volumes of water each day. With their large gills and extremely flat shape, their filtration abilities are highly effective in slow-moving tidal waters.</p>
<p>Oyster reefs more generally also trap and stabilise sediment, which can provide an important buffer against coastal erosion.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=387&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=387&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=387&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=487&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=487&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441426/original/file-20220119-27-mkc9sb.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=487&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The inside of a leaf oyster.</span>
<span class="attribution"><span class="source">Chamara Benthotage</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Threats to leaf oyster reefs</h2>
<p>The current condition of shellfish reefs in Australia <a href="https://theconversation.com/ah-shucks-how-bushfires-can-harm-and-even-kill-our-delicious-oysters-131294">is dire</a>. Declining water quality is recognised as one of the most serious threats to estuaries, with excessive nutrients leading to algal blooms, which can be harmful.</p>
<p>High amounts of sediment can clog up the gills of filter-feeding oysters and can lead to the complete burial of historical oyster reefs. In the past, dredging for oysters, boat harbours and breakwaters has also directly damaged oyster reefs. </p>
<p>Our recent surveys (which aren’t yet published) of leaf oyster beds across four estuaries in northern NSW suggest leaf oysters have disappeared from some locations where they were previously known to live. In the remaining beds, we found 30-67% of the shells to be dead. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441431/original/file-20220119-21-11b7pnw.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fewer leaf oysters lead to poorer water quality.</span>
<span class="attribution"><span class="source">Kirsten Benkendorff</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Their deaths have terrible knock-on effects and are correlated with poor water quality after rain, high acidity, low dissolved oxygen, high nutrients and higher rates of sedimentation.</p>
<p>But one of biggest threats to leaf oyster populations is the lack of knowledge on the species. In particular, the lack of historical information on where they live and how many there are makes it difficult to document how they’ve declined. And this is necessary for listing them as threatened species. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/441432/original/file-20220119-19-1fafbg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">We need more comprehensive maps of leaf oyster distribution.</span>
<span class="attribution"><span class="source">Chamara Benthotage</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Our concern extends beyond the survival and protection of the single species, to the entire ecosystem the leaf oysters underpin. </p>
<p>Improving our understanding of leaf oyster reefs requires more comprehensive mapping of the remaining populations and gaining a better understanding of their life cycle. This includes when they breed, how the larvae develop and where they settle, their age at sexual maturity and how long they live.</p>
<p>This will help us <a href="https://www.marine.nsw.gov.au/knowledge-centre/newsroom/news/leaf-oysters-a-potential-lifeline-in-reef-restoration">include them in reef restoration</a> and estuarine management plans, protecting Australia’s precious, fragile wildlife in the face of a difficult future.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ah-shucks-how-bushfires-can-harm-and-even-kill-our-delicious-oysters-131294">Ah shucks, how bushfires can harm and even kill our delicious oysters</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/164330/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kirsten Benkendorff receives funding from NSW Department of Primary Industries, Fisheries, Coffs Harbour City Council Environmental Levy and the Asia-Pacific Network for Global Change Research.</span></em></p><p class="fine-print"><em><span>Victoria Cole receives funding from the NSW Marine Estate and works for the NSW Department of Primary Industries, Fisheries.</span></em></p><p class="fine-print"><em><span>Chamara Benthotage does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Leaf oysters can form reefs, produce mauve pearls, and reach the size of a dinner plate. They’ve been ignored for far too long.Kirsten Benkendorff, Associate Professor in Marine Biology, Southern Cross UniversityChamara Benthotage, PhD candidate, Southern Cross UniversityVictoria Cole, Adjuct, Southern Cross UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1632222021-08-17T13:44:40Z2021-08-17T13:44:40ZTiny plastic residues threaten Atlantic and Guadeloupean oysters<figure><img src="https://images.theconversation.com/files/414223/original/file-20210802-22-lttbk.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C998%2C688&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Like many marine species, oysters are affected by nanoplastics that pollute the oceans. </span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Our daily use of plastic products is having direct consequences on the health of animals. Roughly one per cent of plastic waste <a href="http://www.cwhc-rcsf.ca/docs/fact_sheets/Wildlife%20ingestion%20of%20microplastics.pdf">ends up in aquatic and terrestrial environments where it can have negative effects on wildlife</a>.</p>
<p>Among these species are oysters, marine mollusks found in many places around the world — as well as on our dinner plates.</p>
<p>In collaboration with the Centre national de la recherche scientifique at the University of Bordeaux, France, our team at the Institut national de la recherche scientifique conducted research to learn more about the combined effects of nanoplastics and arsenic on oysters.</p>
<p>Earlier laboratory studies have shown that nanoplastics can have negative effects on the <a href="https://doi.org/10.1016/j.envpol.2018.08.020.">ability of Pacific oysters to reproduce</a>. Recently, our research team looked at the individual and combined effects of <a href="https://www.sciencedaily.com/releases/2021/05/210504112641.htm">nanoplastics</a> and <a href="https://www.who.int/news-room/fact-sheets/detail/arsenic">arsenic</a> on oysters, and found these pollutants affected some of their most basic functions. We published the results in <a href="https://doi.org/10.1016/j.chemosphere.2021.130331"><em>Chemosphere</em></a> and <a href="https://doi.org/10.3390/nano11051151"><em>Nanomaterials</em></a>.</p>
<h2>The Atlantic oyster is most affected</h2>
<p><a href="https://www.sciencedaily.com/releases/2021/05/210504112641.htm">Nanoplastics</a> are plastics measuring less than one thousandth of a millimetre across. They <a href="https://doi.org/10.1007/978-3-319-16510-3_12">come largely from the degradation of plastic waste released into the environment</a>, but they can also include plastic nanobeads contained in consumer products, like face scrubs, that find their way into natural environments.</p>
<p>These nanoplastics can accrue a variety of environmental contaminants on their surfaces. When an organism ingests the contaminated nanoplastic, the substance can separate from the plastic and accumulate in the organism’s tissues. </p>
<p>Arsenic, a toxic metal, was the most abundantly measured contaminant on the plastic debris our team collected on the beaches of Guadeloupe. Oysters easily accumulate metals through their diet. </p>
<p>We exposed oyster to an environmentally relevant concentration of arsenic. We measured high concentrations of arsenic in the exposed mollusks, and found higher levels in the gills of the Atlantic oyster <a href="https://animaldiversity.org/accounts/Crassostrea_virginica/"><em>Crassostrea virginica</em></a> than in those of the oyster <a href="https://doi.org/10.1016/j.ecss.2019.106333"><em>Isognomon alatus</em></a> found in Guadeloupe.</p>
<p>These results are the first to highlight the difference in sensitivity of oyster species to arsenic.</p>
<p>We also wanted to test whether the combined exposure of nanoplastics and arsenic would increase the accumulation of this metal in mollusks. Fortunately, this was not the case. <a href="https://www.sciencedirect.com/topics/chemistry/bioaccumulation">The bioaccumulation</a> of arsenic did not increase with the presence of these nanoparticles.</p>
<figure class="align-center ">
<img alt="a Crassostrea virginica oyster bed" src="https://images.theconversation.com/files/407530/original/file-20210621-26003-bxbst2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/407530/original/file-20210621-26003-bxbst2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/407530/original/file-20210621-26003-bxbst2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/407530/original/file-20210621-26003-bxbst2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/407530/original/file-20210621-26003-bxbst2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/407530/original/file-20210621-26003-bxbst2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/407530/original/file-20210621-26003-bxbst2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A Crassostrea virginica oyster bed in the Atlantic Ocean, in the coastal United States.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Effects on the basic functions of oysters</h2>
<p>Oysters are filter feeders that eat small bits of algae suspended in the water. We contaminated algae with three types of nanoplastics to test whether these would cause problems to their health.</p>
<p>The nanoplastics we studied were particles of synthetic carboxylated polystyrene with no additives, crushed particles of virgin polystyrene and soiled plastics. The latter were recovered from the beaches of Guadeloupe and then crushed.</p>
<p>Among these three types of plastics, nanoplastics without additives, which are used in detergents and biocides, were the most toxic to both Atlantic and Guadeloupean oysters. After we exposed the oysters to these plastics, the Atlantic oyster showed increases in the expression of genes associated with programmed cell death, as well as an increase in the number of mitochondria — the cell’s energy centres. The Guadeloupean oyster also showed changes in gene expression, but the response was less pronounced. </p>
<p>The combined exposure to nanoplastics and arsenic revealed contrasting effects between our two oyster species. For example, they reduced the individual effects previously seen on the expression of genes involved in the regulation of <a href="https://www.sciencedirect.com/topics/neuroscience/oxidative-stress">oxidative stress</a>, a situation that creates a toxic environment in the cell. Yet their interaction also amplified certain effects, such as an increase in the production of mitochondria.</p>
<p>Researchers are increasingly using gene expression and other tools of molecular biology to understand the effects of environmental contaminants in animals. It is important to develop ultra-sensitive techniques that warn us, in real time, when a contaminant is affecting the health of ecosystems. We must not wait to reach concentrations of pollutants that would cause irreversible effects.</p>
<figure class="align-center ">
<img alt="a dish of oysters served with sauces and lemon" src="https://images.theconversation.com/files/407529/original/file-20210621-35622-1othxrv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/407529/original/file-20210621-35622-1othxrv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/407529/original/file-20210621-35622-1othxrv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/407529/original/file-20210621-35622-1othxrv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/407529/original/file-20210621-35622-1othxrv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/407529/original/file-20210621-35622-1othxrv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/407529/original/file-20210621-35622-1othxrv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Oysters are found on plates all over the planet. It is therefore essential to know their contaminants.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>In the food web</h2>
<p>The next step is to study how nanoplastics are moved into the food web.</p>
<p>Analytical tools are currently being developed to quantify the presence of nanoplastics in biological tissues. For example, “<a href="https://doi.org/10.1021/acs.est.1c01351">pyrolysis gas chromatography</a>” is an analytical tool that can be used to identify a variety of polymers and contaminants in a sample. </p>
<p>It could be used in the future to help determine the amount of particulate matter found in farmed and wild oysters.</p><img src="https://counter.theconversation.com/content/163222/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Valérie Langlois has received financial support from the Agence nationale de la recherche (ANR), the Centre national de la recherche scientifique (CNRS) and the Canada Research Chairs</span></em></p><p class="fine-print"><em><span>Marc Lebordais has received financial support from the Agence nationale de la recherche (ANR), the Centre national de la recherche scientifique (CNRS) and the Canada Research Chairs</span></em></p>Nanoplastics and arsenic can affect some of the most basic functions of oysters.Valérie S. Langlois, Professor/Professeure titulaire, Institut national de la recherche scientifique (INRS)Marc Lebordais, PhD student at the Cervo Brain Research Centre, Institut national de la recherche scientifique (INRS)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1312942020-08-21T03:52:05Z2020-08-21T03:52:05ZAh shucks, how bushfires can harm and even kill our delicious oysters<figure><img src="https://images.theconversation.com/files/320676/original/file-20200316-18023-15fb953.jpg?ixlib=rb-1.1.0&rect=158%2C358%2C4776%2C3284&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Oysters are filter feeders, extracting nutrients from the water, so that makes them very susceptible to water pollution such as that from bushfires.</p>
<p>We are trying to understand how ash from the 2019-20 bushfires has affected the waterways and oyster farms of New South Wales. Their production is worth <a href="https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0006/638700/Aquaculture-Facts-and-Figures-NSW-2020.pdf">more than A$59 million</a> a year. </p>
<p>On the state’s south coast we’re working with oyster farmers as citizen scientists to determine how the ash can lead to harmful algal blooms and oyster deaths.</p>
<p>Over the past two years, farmers have taken more than 9,000 water and oyster samples across 13 estuaries. It’s the largest ever set of water quality and oyster health measurements from oyster-producing estuaries.</p>
<p>This spans the period before, during and after the recent bushfires, providing a unique opportunity to track their impact.</p>
<p>We are still analysing results, but it’s already clear the combination of bushfire ash followed by rainfall led to large increases in microalgae (phytoplankton) in estuaries, including species that can cause harmful algal blooms.</p>
<h2>From coast to coast</h2>
<p>More than half of the value of Australia’s oyster industry comes from NSW. Along the state’s 2,000km coastline, oyster leases are found in 32 estuaries, north to the Tweed River near the Queensland border and south to Wonboyn Lake near the Victorian border.</p>
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Read more:
<a href="https://theconversation.com/summer-bushfires-how-are-the-plant-and-animal-survivors-6-months-on-we-mapped-their-recovery-142551">Summer bushfires: how are the plant and animal survivors 6 months on? We mapped their recovery</a>
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<p>Leases are occupied within estuarine ecosystems, with each of these estuaries having a unique climate, catchment condition, area and entrance type. </p>
<p>Some of the NSW farmers are both oyster farmers and Rural Fire Service members, who faced the unenviable task of trying to save both their livelihoods and their homes at the same time during the 2019-20 fire season. </p>
<p>Oysters provide ecosystem services to waterways in which they grow. They shelter invertebrates such as worms, crabs and snails, and they provide natural breakwalls for shoreline protection.</p>
<p>Via their filter feeding of microalgae, individual oysters can <a href="https://www.sciencedirect.com/science/article/pii/0044848683903137" title="The Pacific oyster Crassostrea gigas: Part I. Feeding behaviour of larvae and adults">filter several litres of seawater per hour</a>, and their presence <a href="https://theconversation.com/the-surprising-benefits-of-oysters-and-no-its-not-what-youre-thinking-90697">improves water quality</a>.</p>
<p>Oysters are used as early-warning biomonitors of waterway health in environmental monitoring programs around the world. </p>
<p>Our new approach to examine the effect of water quality on oyster health is to look at environmental DNA (eDNA). This means we filter water and extract DNA directly from the filtrate. We then use molecular genetic tools to detect and quantify <a href="https://aem.asm.org/content/77/19/7050.short" title="sxtA-Based Quantitative Molecular Assay To Identify Saxitoxin-Producing Harmful Algal Blooms in Marine Waters">harmful microalgae and bacteria</a>. </p>
<h2>The ripple effect: from bushfire to waterway</h2>
<p>The recent bushfires were a timely reminder that what happens on land can impact waterways and that coastal regional areas are susceptible.</p>
<p>The NSW government <a href="https://www.environment.nsw.gov.au/topics/parks-reserves-and-protected-areas/fire/park-recovery-and-rehabilitation/recovering-from-2019-20-fires/understanding-the-impact-of-the-2019-20-fires">says</a> the 2019-20 bushfires covered 5.4 million hectares, roughly 7% of the state. Nationally, more than 17 million hectares were affected.</p>
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<p>Many oyster-growing estuaries were impacted by bushfires in their catchments, especially on the NSW south coast. </p>
<p>While <a href="https://www.theguardian.com/world/2020/feb/07/massive-relief-torrential-rain-douses-bushfires-across-parts-of-australia">rain this summer</a> gave a reprieve from the fires, it can wash ash into the estuaries, bringing with it excessive nutrients (nitrogen and phosphorus) or trace elements (iron, manganese, arsenic, chromium, aluminium, barium and lead).</p>
<p>These supplements can act as fertilisers, triggering the excessive growth of marine microalgae. </p>
<h2>Harmful algal blooms</h2>
<p>The growth of some microalgae is essential, but an excess of certain microalgal species (some of which can naturally produce toxins) can result in <a href="https://www.mdpi.com/1660-3397/15/2/33" title="Recent Trends in Marine Phycotoxins from Australian Coastal Waters">harmful algal blooms</a>.</p>
<p>A harmful algal bloom in an estuary will trigger the closure of oyster harvesting until oysters are clean. One of the largest and most significant harmful algal blooms <a href="https://www.abc.net.au/news/2013-09-05/shellfish-toxin-makes-first-appearance-in-bass-strait/4939514">impacted the Tasmanian shellfish industry</a> in 2012-13. It resulted in an economic loss of around A$23 million. </p>
<p>Bushfire ash may have a more direct impact, by covering the surface of the water so light, which microalgae need to grow, can’t penetrate. This can cause microalgae to die or grow very slowly.</p>
<p>A mass death of microalgae could then change the amount of oxygen available in the water for the growth of oysters and other marine life. Excessive particulate matter in the waterway can also clog the gills of oysters, affecting their ability to filter feed.</p>
<h2>A sustainable food</h2>
<p>In Australia, seafood is very safe to eat. Strict monitoring and testing by <a href="https://www.foodauthority.nsw.gov.au/consumer/keeping-food-safe/summer-eating/seafood-safety">government regulators</a> have ensured illnesses are extremely rare.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/353780/original/file-20200820-14-ta48yh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Six shucked oysters on a plate with a slice of lemon." src="https://images.theconversation.com/files/353780/original/file-20200820-14-ta48yh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/353780/original/file-20200820-14-ta48yh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/353780/original/file-20200820-14-ta48yh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/353780/original/file-20200820-14-ta48yh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/353780/original/file-20200820-14-ta48yh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/353780/original/file-20200820-14-ta48yh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/353780/original/file-20200820-14-ta48yh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Safe to eat: a plate of oysters.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/rosietulips/32813534667/">Flickr/RosieTulips</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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<p>Government regulators are active participants in developing new, more streamlined approaches to food safety monitoring. This combination of scientists, government regulators and oyster farmer citizen scientists working together is a model for a healthy and viable future for oyster aquaculture in the face of challenging events.</p>
<p>After all, oysters are <a href="https://www.marineconservation.org.au/is-aquaculture-sustainable/">regarded</a> as one of the most sustainable forms of animal protein so they need our protection.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/the-surprising-benefits-of-oysters-and-no-its-not-what-youre-thinking-90697">The surprising benefits of oysters (and no, it's not what you're thinking)</a>
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<p>A <a href="https://seagrant.gso.uri.edu/how-eating-more-oysters-could-reduce-greenhouse-gas-emissions/">recent study</a> showed that replacing 10% of animal protein with oysters in the diet of the US population would lead to greenhouse gas savings equivalent to taking 11 million cars off the road. </p>
<p>Australia also has a <a href="http://aquaticcommons.org/9751/">rich heritage</a> of oyster aquaculture. For thousands of year, oysters were a staple food of First Nations people.</p>
<p>The <a href="https://www.dpi.nsw.gov.au/fishing/fish-species/species-list/sydney-rock-oyster">Sydney Rock Oyster</a> is one of the native species that’s been cultivated as a profitable industry in Australia since European habitation.</p>
<p>They’ve been farmed sustainably for more than 150 years. These oysters are still the basis of a profitable industry, which has grown in size over recent years. </p>
<p>We hope the results of our research will ensure the long-term viability of an industry <a href="https://www.agriculture.gov.au/abares/research-topics/fisheries/fisheries-and-aquaculture-statistics">worth millions of dollars</a> to the Australian economy but, just as importantly, helps support many coastal communities.</p>
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<p class="fine-print"><em><span>Shauna Murray receives funding from the Fisheries Research and Development Corporation, the Australian Research Council, and the Food Agility Cooperative Research Centre.</span></em></p><p class="fine-print"><em><span>Penelope Ajani receives funding from the Fisheries Research and Development Corporation, the Australian Research Council, and the Food Agility Cooperative Research Centre.</span></em></p>Bushfires not only destroy things on land, they can also have an impact on our seafood industry including our oyster farms.Shauna Murray, Associate Professor; Faculty of Science, University of Technology SydneyPenelope Ajani, Chancellors Post Doctoral Fellow, Climate Change Cluster, University of Technology SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1102332019-05-02T14:15:09Z2019-05-02T14:15:09ZThe world’s most degraded marine ecosystem could be about to make a comeback<figure><img src="https://images.theconversation.com/files/272297/original/file-20190502-103045-y2sb7f.jpg?ixlib=rb-1.1.0&rect=36%2C0%2C4096%2C2722&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Zoological Society London</span>, <span class="license">Author provided</span></span></figcaption></figure><p>When we think of mass habitat extinction, colourful, diverse and highly visible ecosystems such as tropical rain forests and coral reefs come to mind. Approximately half of global <a href="https://wwf.panda.org/our_work/oceans/coasts/coral_reefs/">shallow water coral reefs</a> and <a href="https://www.nature.com/articles/nature14967">forests</a> have been lost over the last few hundred years, but there are glimmers of hope. <a href="http://www.fao.org/3/a-i4793e.pdf88">Deforestation rates are declining</a> and some corals have shown <a href="https://theconversation.com/why-theres-still-hope-for-our-endangered-coral-reefs-104503">resilience to stress from climate change</a>.</p>
<p>A far less visible ecosystem crisis has occurred relatively recently beneath the ocean’s surface. A study revealed that <a href="https://academic.oup.com/bioscience/article/61/2/107/242615">85% of global oyster reefs</a> have been lost over the last 150 years. Of those remaining, over one third are so depleted that they no longer function as ecosystems, particularly those in Europe, North America and Australia. Only a few healthy oyster reefs remain in South America, and even these are 50% of their prior abundance, making oyster reefs <a href="https://academic.oup.com/bioscience/article/61/2/107/242615">one of the most threatened habitats on Earth</a>.</p>
<p>Oysters are “ecosystem engineers” like corals – they create three-dimensional structures as they settle and grow on each other. Left undisturbed, these oyster reefs provide a habitat for an <a href="https://www.sciencedirect.com/science/article/pii/S0169534701023308">incredible biodiversity of organisms</a>, serving as a food source, nursery ground and refuge for many species, <a href="https://www.int-res.com/abstracts/meps/v264/p249-264/">boosting fish stocks</a>.</p>
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<p>Oysters also have an incredible ability to clean seawater. A single oyster can filter almost <a href="https://www.sciencedirect.com/science/article/pii/S0304380014005961">200 litres of seawater daily</a>, eating the phytoplankton and organic matter suspended within it. Oysters <a href="https://www.int-res.com/articles/feature/m480p001.pdf">improve water quality and clarity</a>, preventing large scale algal blooms and the potential consequences of mass fish mortality and deadzones due to depleted oxygen.</p>
<p>Removing oyster reefs increases wave energy and <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0022396">erosion of saltmarshes and the corresponding coastline</a>. Just as tropical coral reefs protect mangrove forests, oyster reefs provide coastal protection for important temperate ecosystems such as seagrass and saltmarshes. </p>
<p>As climate change and pollution destroy marine life, the need for vast oyster reefs has never been greater. Sadly, this vital habitat is at its nadir when we have <a href="https://onlinelibrary.wiley.com/doi/epdf/10.1111/cobi.12452">almost no living memory of its natural state</a>.</p>
<h2>The oyster reefs of yesteryear</h2>
<p>Humans have been hand harvesting oysters since the Stone Age and cultivating them since Roman times. But oyster extraction reached <a href="https://www.pnas.org/content/pnas/101/35/13096.full.pdf">fantastic proportions</a> from the mid-1800s as mechanised fishing boats replaced older fleets. </p>
<p>Chesapeake Bay – meaning “great shellfish” – in the US was named by the Algonquin Indians because of the miles of incredibly dense oyster reefs that <a href="https://www.chesapeakebay.net/discover/history/captain_john_smith">“lay thick as stones”</a> in 1608. Between 1860 and 1920, <a href="https://www.cbf.org/document-library/cbf-reports/Oyster_Report_for_Release02a3.pdf">three quarters of these reefs</a> had been destroyed and by 1940 <a href="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.632.1289&rep=rep1&type=pdf">they had been almost entirely wiped out</a>. </p>
<p>Across the Atlantic in Europe, oyster reefs were once plentiful and thought to be inexhaustible. The Olsen piscatorial atlas of 1883 depicts large oyster grounds at a depth of 34 metres in the North Sea, stretching from Helgoland, off the coast of Germany, to the Dogger Bank, between UK and Denmark, and through the English Channel. Though recently extirpated, oysters were <a href="https://www.sciencedirect.com/science/article/pii/S0006320717308030#f0005">once abundant in the Firth of Forth</a> on Scotland’s east coast. </p>
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<a href="https://images.theconversation.com/files/271967/original/file-20190501-113858-9ueg2k.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/271967/original/file-20190501-113858-9ueg2k.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/271967/original/file-20190501-113858-9ueg2k.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=771&fit=crop&dpr=1 600w, https://images.theconversation.com/files/271967/original/file-20190501-113858-9ueg2k.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=771&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/271967/original/file-20190501-113858-9ueg2k.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=771&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/271967/original/file-20190501-113858-9ueg2k.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=969&fit=crop&dpr=1 754w, https://images.theconversation.com/files/271967/original/file-20190501-113858-9ueg2k.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=969&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/271967/original/file-20190501-113858-9ueg2k.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=969&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Historic distribution of European flat oyster (<em>Ostrea edulis</em>) reefs in the North Sea.</span>
<span class="attribution"><a class="source" href="https://www.platteoester.nl/dutch-flat-oyster-consortium-poc/">Olsen, 1883.</a></span>
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<p>Roads and towns were built on shucked oyster shells in the US and Britain while shell piles towered one trillion tall in France. In 1864, <a href="https://www.bfn.de/fileadmin/BfN/meeresundkuestenschutz/Dokumente/2015-06-02_Auster_Machbarkeitsstudie-barrierefrei-english.pdf">700m European oysters were consumed in London alone</a>.</p>
<p>The European native oyster (<em>Ostrea edulis</em>) population has declined by 95% since the 1950s, and oysters are now <a href="https://hmr.biomedcentral.com/articles/10.1007/BF01999132">extinct in some regions of Europe</a>, such as the Wadden Sea along the coast of Germany.</p>
<p>Removing these vast ecosystems has deprived the sea of essential services, <a href="https://www.int-res.com/abstracts/meps/v341/p303-307/">reducing water quality</a>. There’s even speculation that the North Sea is especially murky today <a href="https://new.foe.co.uk/sites/default/files/downloads/what_has_nature_ever_done0.pdf">because oysters are no longer around</a>.</p>
<p>Destructive fishing that exceeds reproduction rates and removes habitat is the main cause of this ecosystem’s demise, but pollution, climate change, invasive species and shellfish diseases have further decimated remnant oyster stocks. It’s clear that active intervention is needed to <a href="https://peerj.com/articles/6431/">turn the tide for oysters</a>.</p>
<h2>Restoring oyster reefs</h2>
<p>Efforts to restore oyster reefs have already had <a href="https://www.nature.org/en-us/about-us/where-we-work/united-states/maryland-dc/stories-in-maryland-dc/oyster-restoration-in-maryland/">success in the US</a> and there are projects emerging in the UK and Europe.</p>
<p>In southern England, the Solent Oyster Restoration Project was established in 2017 to <a href="https://www.bluemarinefoundation.com/wp-content/uploads/2015/11/20160525_Solent-Oyster-Restoration-Project_Management-Plan_Final-version.pdf">reseed the Solent</a> strait with 5m oysters. Since then, more than 20,000 oysters have been placed in novel restoration aquaculture cages, suspended underneath <a href="https://uopnews.port.ac.uk/2017/04/20/portsmouth-researchers-work-with-ben-fogle-on-oyster-project-to-clean-up-the-solent/">marina pontoons across the Solent</a>. These cages are designed to <a href="https://www.mdlmarinas.co.uk/news/more-oyster-cages">pump out larvae</a> which settle on the surrounding seabed, where 30,000 juvenile oysters reared in hatcheries have <a href="https://www.bbc.co.uk/news/uk-england-hampshire-46835714">already been reintroduced</a>.</p>
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<a href="https://images.theconversation.com/files/272229/original/file-20190502-103068-gkn2vg.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272229/original/file-20190502-103068-gkn2vg.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/272229/original/file-20190502-103068-gkn2vg.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=802&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272229/original/file-20190502-103068-gkn2vg.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=802&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272229/original/file-20190502-103068-gkn2vg.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=802&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272229/original/file-20190502-103068-gkn2vg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1008&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272229/original/file-20190502-103068-gkn2vg.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1008&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272229/original/file-20190502-103068-gkn2vg.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1008&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A cage full of oysters ready to reseed the seabed.</span>
<span class="attribution"><span class="source">Blue Marine Foundation</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The <a href="https://nativeoysternetwork.org">Native Oyster Network</a> in the UK and Ireland and the <a href="https://noraeurope.eu/">Native Oyster Restoration Alliance</a> across Europe aim to restore native oysters around the north-west Atlantic. Both established in 2017, these networks are bringing together scientists, fishers, conservationists and governments to bring back a forgotten ecosystem. </p>
<p>Restoring European oyster beds and reefs is possible, but there is no quick fix. Work will take years and decades and depend on multinational cooperation and effective policy to protect habitats and regulate fishing. Nevertheless, recent efforts give hope we are at the beginning of a journey to restore a forgotten ecosystem to its once magnificent state.</p><img src="https://counter.theconversation.com/content/110233/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joanne Preston is co-founder of the UK & Ireland Native Oyster Network and receives funding from Blue Marine Foundation, John Ellerman Foundation and the Environment Agency.</span></em></p>Coral reefs get a lot of attention, but the world has lost almost all of its vital oyster reefs in the last few centuries.Joanne Preston, Principal Lecturer in Marine Biology, University of PortsmouthLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1054792018-11-06T11:46:07Z2018-11-06T11:46:07ZHurricanes and water wars threaten the Gulf Coast’s new high-end oyster industry<figure><img src="https://images.theconversation.com/files/243967/original/file-20181105-74783-1ifvea0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Gulf Coast oysters on the half shell at Wintzell's, Mobile, Ala. </span> <span class="attribution"><a class="source" href="https://flic.kr/p/bofSen">donireewalker</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>For Cainnon Gregg, 2018 started out as a great year. After leaving his job as an installation artist to become a full-time oyster farmer in Wakulla County, Florida in 2017, Gregg began raising small oysters in baskets or bags suspended in the shallow, productive coastal waters of Apalachicola Bay. </p>
<p>Raising oysters “off-bottom” this way takes a lot of time and money, but has a big potential payoff. They are destined for the high-end raw bar market, where offerings are denoted by specific appellations, like “Salty Birds” (Cainnon’s oysters), “Navy Coves” (from Alabama) and “Murder Points” (also from Alabama), and can retail for twice the price of oysters harvested from traditional on-bottom reefs.</p>
<p>When Hurricane Michael made landfall at Mexico Beach, Florida, on Oct. 10, 2018, it dealt a devastating blow to this nascent industry. Preliminary reports indicate significant damage and heavy crop losses. Raising oysters by any method is not an easy job, but if off-bottom farming can become established along the Gulf Coast, it could give the industry a much-needed boost, give consumers more choices, and provide a new stream of environmental benefits.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/BdXjq1PDEvP/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Premium products</h2>
<p>The United States produces multiple species of oysters, but historically the eastern oyster (<em>Crassostrea virginica</em>) has accounted for over 70 percent of total harvests. The Gulf Coast generally accounts for 80 percent of those, with production generating <a href="https://repository.library.noaa.gov/view/noaa/16121">US$1 billion in annual revenues</a>. </p>
<p>Louisiana is the national leader in oyster production, with a handful of other states vying for second place, including Washington, South Carolina and Texas. However, when states are ranked by value per unit – that is, total value over total landings – states like Massachusetts, Maryland and Virginia dominate.</p>
<p>This is partly due to regional differences in how oysters are grown and marketed. Traditional harvesting of oyster reefs on the sea bottom still dominates in the Gulf region. These oysters are generally sold as a commodity, appearing on menus as simply “oysters” or “Gulf Coast oysters.” </p>
<p>Elsewhere, most oysters come from off-bottom farming and tend to be marketed under the names of specific reefs, growers or appellations. Off-bottom oyster farming has been a <a href="https://www.fisheries.noaa.gov/national/aquaculture/us-aquaculture">major driver in the growth of marine aquaculture production nationally</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/243964/original/file-20181105-74757-hbqis0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Oysters are grown in cages at Island Creek Oyster Farm in Duxbury, Mass.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/bDGAqU">MA Office of Travel and Tourism/Hanks</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The Gulf’s first commercial off-bottom farms started up in Alabama and Louisiana in 2010. Today more than 50 farms are operating in Florida, Alabama and Louisiana, with permits pending for others in Mississippi. Harvest data are limited, but in Alabama alone, eleven farms collectively reported <a href="http://masgc.org/assets/uploads/publications/1312/alabama_shellfish_aquaculture_situation_and_outlook_report_2016.pdf">nearly $2 million in sales in 2016</a>. In recent years Alabama has ranked among the top five states in per-unit value.</p>
<h2>Reasons to diversify</h2>
<p>Raising off-bottom oysters is good for more than oystermen’s bottom lines. Oysters improve water clarity by filtering out phytoplankton, thereby removing nitrogen from the water column. They also provide forage grounds and habitat for fish and act as breakwaters, protecting nearby shorelines. </p>
<p>Off-bottom farms deliver the same types of benefits as traditional on-bottom reefs, although in slightly different ways and at different times, depending on local conditions and farming methods. In our view, raising oysters in multiple ways is beneficial because it avoids putting all of our eggs in one basket, so to speak, and makes the industry more resilient. </p>
<p>We come at this topic from different perspectives. <a href="https://scholar.google.com/citations?user=yPXqOj8AAAAJ&hl=en">Daniel Petrolia</a> focuses on the economics of <a href="http://dx.doi.org/10.3368/le.92.2.292">coastal resources</a> and <a href="http://dx.doi.org/10.3368/le.91.2.272">natural hazards</a>. <a href="https://scholar.google.com/citations?user=DzRuv-cAAAAJ&hl=en">William Walton</a> directs Auburn University’s <a href="https://mifralabgroup.wixsite.com/home">Marine Invertebrate Fisheries, Restoration and Aquaculture Lab</a>. We have worked together since 2011 to better understand <a href="https://restoreactscienceprogram.noaa.gov/projects/oyster-planning-tool">oyster habitats</a>, <a href="https://doi.org/10.1017/aae.2016.30">evaluate market opportunities</a> and identify and tackle challenges for the new industry. Disaster preparation and recovery clearly are top priorities.</p>
<p>We see off-bottom oyster farming as especially interesting economically, given its novelty on the Gulf Coast, the new market opportunities it affords growers and the diversity it brings to the Gulf Coast’s oyster habitat “portfolio.” It also offers new choices for people who like to eat Gulf Coast oysters.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/9iPXluPr7V0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Marketing video from Panacea Oyster Co-Op in Wakulla County, Florida.</span></figcaption>
</figure>
<h2>Natural and man-made disasters</h2>
<p>Hurricanes and storms pose serious threats to the Gulf oyster industry. They can harm reefs by burying them in sediments or drastically altering water salinity. </p>
<p>Storm impacts tend to be highly localized. Prior to Hurricane Katrina in 2005, Mississippi was the fourth-largest oyster-producing state in the nation. Katrina <a href="https://www.st.nmfs.noaa.gov/commercial-fisheries/commercial-landings/annual-landings/index">slashed the state’s output by 80 percent that year</a>, and fishermen were unable to harvest oysters at all in 2006. Production recovered somewhat over the next several years, but Mississippi harvests have remained around one-tenth of pre-Katrina levels. </p>
<p>Louisiana, whose oyster reefs lie just west of where Katrina made landfall, saw just a 6 percent drop in production following Katrina. The impacts of the Deepwater Horizon disaster were shorter-lived, but Louisiana’s 2010 harvest was cut in half due to precautionary closures during and after the spill. Oysters were also killed by releases of fresh water from the Mississippi River, which were conducted in an effort to keep oil out of coastal estuaries.</p>
<p>Storms are not the only threat. Florida and Georgia have been fighting for decades over <a href="https://www.tampabay.com/news/environment/Supreme-Court-finally-rules-on-Florida-s-30-year-water-war-with-Georgia-And-it-s-not-over-_169506140">allocating water from the Apalachicola River</a>; when Georgia draws a high level of water, it reduces freshwater flow to Apalachicola Bay, which can lead to increases in oyster mortality from predation and disease. And harmful algal blooms, such as <a href="https://theconversation.com/what-is-causing-floridas-algae-crisis-5-questions-answered-101305">Florida’s massive 2018 red tide outbreak</a>, can close waters to harvesting.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1012001134343573505"}"></div></p>
<p>Beyond direct impacts on oyster farms, Hurricane Michael damaged state laboratories that conduct water quality testing required to re-open waters to harvesting. Testing delays could lead to prolonged closures and even affect areas not hit by the storm. Michael also disrupted red tide sampling in several Panhandle counties. In Gulf and Escambia counties, red tide concentrations actually <a href="http://myfwc.com/RedTideStatus">increased in late October</a>.</p>
<p>Farmers will be looking for more oyster seed – the small oysters that they need to restock their bags and baskets. This could drive up demand and strain the industry’s capacity. Unlike crop farmers on land, oyster farmers cannot buy subsidized insurance to help them with losses of oysters and gear, so those who suffered heavy damage will be challenged to rebuild their operations.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=558&fit=crop&dpr=1 600w, https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=558&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=558&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=701&fit=crop&dpr=1 754w, https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=701&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/243952/original/file-20181105-83632-cmk90h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=701&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Hurricane Michael failed to break up the red tide outbreak along Florida’s west coast.</span>
<span class="attribution"><a class="source" href="http://myfwc.com/RedTideStatus">Florida Fish and Wildlife Conservation Commission</a></span>
</figcaption>
</figure>
<h2>Not an easy business</h2>
<p>As we write, oyster farmers in the Panhandle are still inspecting their farms for damage and seeing how their oysters fared. Some estimate that they may have lost <a href="https://www.nbcnews.com/news/us-news/hurricane-michael-may-have-dealt-deadly-blow-florida-s-nascent-n922356">60 to 90 percent of their crops</a>.</p>
<p>Oystermen have strategies for dealing with hurricanes, such as sinking baskets loaded with oysters to the bottom before the storm arrives. But they can only reduce risk, not eliminate it. The threat of <a href="https://tidesandcurrents.noaa.gov/publications/techrpt86_PaP_of_HTFlooding.pdf">rising sea levels</a> and <a href="https://opensky.ucar.edu/islandora/object/technotes:552">more intense storms</a> will force them to continue adapting and improving their strategies. </p>
<p>Earlier this year, Cainnon Gregg started selling “Salty Birds” to some of the finest oyster bars in the South. Two days after Hurricane Michael passed through, he was back on the water checking lines and making repairs. “There’s nothing easy about any of this, and all you can do is get back out here and get back to work,” he said. He could have been speaking for all Gulf oystermen.</p><img src="https://counter.theconversation.com/content/105479/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Daniel R. Petrolia receives funding from the National Oceanic and Atmospheric Administration (NOAA), the Mississippi-Alabama Sea Grant Consortium, and the Bureau of Ocean Energy Management. </span></em></p><p class="fine-print"><em><span>William C. Walton receives funding from National Sea Grant, Mississippi-Alabama Sea Grant Consortium and the USDA. He is affiliated with Oyster South, a non-profit dedicated to advancing oyster aquaculture in the southern US.</span></em></p>Oysters are big business along the Gulf Coast, but raising them off-bottom – which yields a premium product – is just starting there. Hurricane Michael showed it won’t be easy.Daniel R. Petrolia, Professor of Agricultural Economics, Mississippi State UniversityWilliam C. Walton, Associate Professor of Fisheries Science, Auburn UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/964562018-05-22T21:01:17Z2018-05-22T21:01:17ZWhy you may never eat raw oysters again<figure><img src="https://images.theconversation.com/files/219516/original/file-20180517-26286-f3sb76.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Eating raw oysters can put you at risk of food-borne illnesses, such as norovirus, hepatitis A and salmonella. And, sadly, hot sauce, lemon juice and alcohol do not reduce the risks.</span> <span class="attribution"><span class="source">(Shutterstock))</span></span></figcaption></figure><p>Many people look forward to raw oysters, and raw oyster bars are popular at some trendy restaurants. However, they (along with other under-cooked seafood) can put you at risk for food-borne illnesses.</p>
<p>Recently, <a href="http://www.cbc.ca/news/canada/british-columbia/norovirus-oysters-april-2018-1.4649715">many people became ill in British Columbia, Alberta and Ontario</a> after eating raw oysters harvested from B.C. farms. </p>
<p>Although the actual causes of the contamination are still unknown, <a href="https://www.canada.ca/en/public-health/services/public-health-notices/2017/public-health-notice-ongoing-outbreak-norovirus-gastrointestinal-illnesses-linked-undercooked-oysters-british-columbia.html">human sewage in the marine environment is the likely culprit</a> in this outbreak. </p>
<p><a href="https://www.cdph.ca.gov/Programs/OPA/Pages/NR18-027.aspx">People in the United States have also become sick</a> from eating these Canadian raw oysters. </p>
<p>Norovirus is actually the most common cause of food-borne illness caused by the consumption of bivalve shellfish contaminated with human fecal matter. In fact, some recent research done in the United Kingdom found that <a href="http://www.foodsafetynews.com/2018/05/norovirus-found-in-almost-70-percent-of-oysters-for-sale-in-uk/#.Wv19O4iUubg">almost 70 per cent of the raw oysters sold in the U.K. contain norovirus</a>, although it is uncertain if all of the virus is actually infectious. </p>
<p>Oyster-associated norovirus outbreaks commonly result from contamination at the source in the growing waters. Oyster beds themselves can become contaminated due to land-based sewage outflow or sewage disposal from oyster harvesters.</p>
<h2>Can you tell if a raw oyster is bad?</h2>
<p>No, an oyster that contains harmful bacteria or viruses does not look, smell or even taste different from any other oyster.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/219517/original/file-20180517-26286-13mmrjl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219517/original/file-20180517-26286-13mmrjl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219517/original/file-20180517-26286-13mmrjl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219517/original/file-20180517-26286-13mmrjl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219517/original/file-20180517-26286-13mmrjl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219517/original/file-20180517-26286-13mmrjl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219517/original/file-20180517-26286-13mmrjl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The safest way to eat oysters is to cook them until they reach an internal temperature of 90˚C.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Besides norovirus, there are a number of other bacteria and viruses that we need to be concerned with in raw oysters. </p>
<p>The most important bacteria are two in the genus Vibrio. One is called <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa051594">Vibrio parahaemolyticus</a> and the other Vibrio vulnificus. The latter bacterium can cause more severe illness, but are more often a problem in the U.S. than in Canada. </p>
<p><a href="http://www.dx.doi.org/10.1128/AEM.71.2.893-897.2005">Salmonella has also been found in raw oysters</a>. And, when it comes to viruses, hepatitis A can be found in raw oysters and cause illness, although norovirus is the one that has caused most of the problems of late.</p>
<h2>How do raw oysters become contaminated?</h2>
<p>Human sewage in the marine environment is believed to be the most probable cause of oyster contamination with norovirus. </p>
<p>But Vibrio bacteria are believed to be a natural part of the marine environment where oysters live. It is only when water temperatures rise that these bacteria can become a problem. </p>
<p>In fact, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4772208/pdf/ijerph-13-00188.pdf">global warming is thought by some to be responsible for some outbreaks linked to Vibrio species</a>. </p>
<p>Because oysters feed by filtering water, both bacteria and viruses can actually concentrate themselves in the tissues of the oysters before they are eaten by consumers.</p>
<h2>Who is most at risk of infection?</h2>
<p>Acute gastrointestinal illnesses such as norovirus and vibriosis are common in North America, and can affect all age groups. </p>
<p>However, pregnant women, people with compromised immune systems, young children and the elderly are at risk for developing more serious complications. </p>
<p>For a certain type of Vibrio bacteria, which is more common in the U.S., <a href="https://www.fda.gov/Food/ResourcesForYou/HealthEducators/ucm085365.htm">people with underlying health conditions, such as liver disease, are at a higher risk of more serious complications or even death</a>. </p>
<h2>How to purchase oysters safely</h2>
<p>First, shop from reliable sources and choose fresh oysters with intact shells and without abnormal odour. When the shell is tapped, it should close tightly. Throw away any oysters with shells already opened.</p>
<p>Check the expiry date of pre-packaged shucked oysters. Ensure they are stored properly at 4˚C or below for chilled products, or at -18˚C or below for frozen products.</p>
<p>It is best to place raw, store-bought oysters into a cold thermos bag when transporting them home. This will minimize the time that the oysters are exposed to room temperature, which favours the growth of bacterial pathogens such as Vibrio. </p>
<p>Chilled oysters should be consumed within one to two days. Oysters in the shell should be placed in containers with a cover to prevent cross-contamination in the refrigerator.</p>
<h2>How to cook oysters at home</h2>
<p>To protect yourself, do not eat oysters raw or under-cooked. The safest way is to <a href="https://www.seafoodhealthfacts.org/seafood-safety/general-information-patients-and-consumers/seafood-safety-issues-specific-products-0">cook your oysters</a> until they reach an internal temperature of 90˚C.</p>
<p>In the shell: After the shells open, you should boil the live oysters for another three to five minutes. Also, do not cook too many oysters in the same pot because the ones in the middle may not get fully cooked. Finally, discard any oysters that do not open during cooking.</p>
<p>In a steamer: Add oysters to water that is already steaming and cook the live oysters for four to nine minutes.</p>
<p>Shucked products should be boiled for three minutes, fried at 375°F for at least three minutes or baked at 232°C (450°F) for 10 minutes.</p>
<p>Be sure to wash your hands, utensils and surfaces well with hot water and soap after you have handled raw oysters. You do not want to cross-contaminate other ready-to-eat foods in your kitchen. </p>
<h2>A few oyster myths</h2>
<p><strong>1. You only get sick from eating oysters during the warmer months of the year.</strong></p>
<p>While it is true that most vibriosis cases occur during the warmer months of the year, when the water temperatures are higher and there is a better chance of the Vibrio bacteria growing more rapidly, cases have been reported all year round. </p>
<p>For norovirus, a number of studies have found that you can actually find higher levels in commercially harvested shellfish during the winter. <a href="https://academic.oup.com/jid/article/181/Supplement_2/S284/1023787">Some studies have shown that there is a cold weather peak in relation to the number of norovirus gastroenteritis cases that occur</a>.</p>
<p><strong>2. If you avoid eating raw oysters from polluted waters, you will be safe.</strong></p>
<p>False. Vibrio bacteria are not a result of pollution as they are natural inhabitants of the marine environment. So, although oysters should always be obtained from reputable sources, eating oysters from “clean” waters or in reputable restaurants with a high turnover does not guarantee that you will not get sick.</p>
<p><strong>3. Eating raw oysters with hot sauce and lemon juice will kill the bacteria and viruses that can cause food-borne illness.</strong></p>
<p>No, this is false. Hot sauce and/or lemon juice will not significantly affect any of the food-borne pathogens.</p>
<p><strong>4. Eating raw oysters while drinking alcohol will kill the bacteria and viruses that can cause food-borne illness.</strong></p>
<p>Again, this is false.</p><img src="https://counter.theconversation.com/content/96456/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeffrey M. Farber does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>In the wake of a norovirus outbreak traced to raw oysters from British Columbia, our expert explains how to eat this culinary delicacy safely.Jeffrey M. Farber, Professor of Food Safety, University of GuelphLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/906972018-02-18T19:13:46Z2018-02-18T19:13:46ZThe surprising benefits of oysters (and no, it’s not what you’re thinking)<figure><img src="https://images.theconversation.com/files/204773/original/file-20180205-19918-f0cg36.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Oysters can do a lot more than they're given credit for.</span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>Think of oysters, and what comes to mind? You’ll probably picture a plate of seafood with a generous squeeze of lemon, or you might think of oysters’ <a href="https://theconversation.com/mondays-medical-myth-eating-oysters-makes-you-randy-4588">reputation as an aphrodisiac</a>. But oysters have many talents beyond their famed gastronomic (and other) qualities.</p>
<p>Oysters also help coastal ecosystems in many different ways, from cleaning the water to sheltering other animals. Yet despite their usefulness, newly published research led by the Nature Conservancy shows that <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0190914">more than 90% of Australia’s shellfish reefs have been lost since European settlement</a>. Unless they can be restored, we risk missing out on their many benefits.</p>
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Read more:
<a href="https://theconversation.com/huge-restored-reef-aims-to-bring-south-australias-oysters-back-from-the-brink-77405">Huge restored reef aims to bring South Australia's oysters back from the brink</a>
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<p>Oysters are multi-talented marine warriors with an impressive bag of tricks up their calcareous sleeves. Their filter-feeding improves water quality and nutrient cycling. They provide safe haven for young fish and small invertebrates, reduce coastal erosion, and even soak up carbon. </p>
<p>To capture these hidden talents, restoration of Australia’s <a href="https://blogs.adelaide.edu.au/environment/2017/07/24/oyster-reef-restoration-series-history-of-australias-oyster-reefs/">once abundant oyster reefs</a> is on the national agenda, culminating in the <a href="https://theconversation.com/huge-restored-reef-aims-to-bring-south-australias-oysters-back-from-the-brink-77405">Southern Hemisphere’s largest oyster reef restoration project</a>, currently underway in South Australia. The latest research in this area will be showcased this week at a <a href="https://www.shellfishrestoration.org.au/news-events/19th-international-conference-on-shellfish-restoration-shellfish-reef-restoration-network-meeting/">conference</a> in Adelaide.</p>
<h2>Living on the edge</h2>
<p>Life is tough for animals living on intertidal rocky shores, such as snails and crabs. These animals experience extreme temperature swings during low tide, and are vulnerable to marine predators during high tide. </p>
<p>But oysters can help, by providing shelter for small invertebrates, giving them refuge from both weather and predators. The convoluted shells of oysters cast shade and trap moisture during low tide. This <a href="http://onlinelibrary.wiley.com/doi/10.1111/1365-2656.12757/full">buffers the extremities of climate that animals’ experience</a>, with temperatures up to 10°C cooler than adjacent habitat during hot days. </p>
<p>At the landscape scale, <a href="http://onlinelibrary.wiley.com/doi/10.1890/15-0651.1/full">oysters remove the influence that changes in climate over latitude have on invertebrate communities</a>. In dampening the extremities of climate that organisms experience, oysters can buy intertidal species some time to adapt to climate change.</p>
<p>Another major benefit of oysters comes from their feeding habits. Oysters are filter feeders that improve water clarity by drawing in particles from the water column and sending them to the seafloor. A single oyster is like a pool pump, filtering up to 100 litres of water a day. Multiply that by the millions of oysters on a reef, and they become the kidneys of the coast, capable of <a href="https://link.springer.com/article/10.1007/s12237-012-9559-y">filtering entire estuaries within a matter of days</a>. </p>
<p>Clearer waters let in more sunlight. Meanwhile, the deposition of oyster faeces creates a nutrient-rich seafloor. This combination allows seagrass to thrive, in turn encouraging species such as burrowing clams, worms and crabs, and ultimately underpinning the entire coastal food web.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/-B6VV5kYmxU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Oysters sheltering fish (video by Francisco Martinez Baena).</span></figcaption>
</figure>
<p>Furthermore, these sediments promote the growth of particular bacteria that <a href="http://onlinelibrary.wiley.com/doi/10.4319/lo.2002.47.5.1367/full">convert excess organic nitrogen into inert nitrogen gas</a>, thus preventing algal blooms that can harm other species. This process has been <a href="https://academic.oup.com/bioscience/article/62/10/900/238172">valued at more than US$4,000 per hectare per year</a>. </p>
<p>Oysters’ filter-feeding is so efficient that Swedish researchers have evaluated it as a <a href="http://onlinelibrary.wiley.com/doi/10.1002/9780470960967.ch8/summary">cost-effective alternative to wastewater treatment plants</a>. Across the Atlantic, the loss of oyster reefs in Chesapeake Bay, the largest estuary on North America’s east coast, transformed the ecosystem from clear waters teeming with fish, to a murky, algae-choked mess. </p>
<h2>Living defences</h2>
<p>Sea levels and storm surge erosion are on the rise. In response, we are fortifying our coasts with solid seawalls. But these merely deflect wave energy, potentially shifting the problem along the coast. </p>
<p>Living oyster reefs, in contrast, dissipate wave energy. And unlike seawalls, their <a href="https://www.nature.com/articles/nclimate2216?WT.feed_name=subjects_ecosystem-services">growth can outpace sea level rise</a>. Oyster reefs’ role as <a href="http://www.oceanwatch.org.au/community/current-programs/">natural breakwaters</a> could be particularly helpful in estuaries where high boat traffic intensifies shoreline erosion, such as Sydney Harbour. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205821/original/file-20180211-51710-xw4fqy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sydney Harbour’s rock oysters can play a protective role.</span>
<span class="attribution"><span class="source">Maria Vozzo</span></span>
</figcaption>
</figure>
<p>In sheltered bays, Sydney rock oysters grow vertically, providing a haven for invertebrates looking for somewhere to live. On exposed shorelines with intense wave action, oysters grow more horizontally, reducing drag against wave action. These hardy flattened oysters also shelter invertebrates, most of which would be dislodged in the oysters absence.</p>
<p>Oysters’ inherent adaptability has long been appreciated by aquaculture managers. The New South Wales oyster industry, the state’s oldest and most valuable aquaculture industry, has <a href="http://archive.dpi.nsw.gov.au/content/science-and-research/science-news/fisheries/aquaculture/disease-resistant-oysters">selectively bred oysters for more than 25 years</a>, breeding the best oysters together en masse to promote traits such as fast growth and disease-resistance. </p>
<p>But new techniques allows the production of oysters with specific characteristics while avoiding inbreeding, by <a href="https://www.selectoysterco.com.au/family-breeding-program">mating individual parents with desired traits</a>. This precise breeding could allow researchers to tailor-make oysters to endure specific environmental conditions, offering a boost to the various restoration projects around the world.</p>
<p>The future is looking bright for oyster restoration in Australia. Following <a href="https://theconversation.com/huge-restored-reef-aims-to-bring-south-australias-oysters-back-from-the-brink-77405">South Australia’s lead</a>, <a href="http://www.natureaustralia.org.au/our-work/oceans/restoring-shellfish-reefs/port-phillip-bay/">Victoria</a>, <a href="http://www.natureaustralia.org.au/our-work/oceans/putting-the-oyster-reefs-back-into-oyster-harbour/">Western Australia</a> and <a href="http://restorepumicestonepassage.org/">Queensland</a> are increasing their efforts to re-establish reefs where they once thrived. New South Wales, meanwhile, is <a href="http://www.worldharbourproject.org/workgroups/green-engineering/">using green engineering techniques to enhance oyster communities on seawalls</a>.</p>
<p>With luck, in years to come oysters will still be sharing their many talents with us, and with their fellow marine creatures.</p><img src="https://counter.theconversation.com/content/90697/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian McLeod receives research funding from the National Environmental Science Program Tropical Water Quality Hub and Marine Biodiversity Hub.</span></em></p><p class="fine-print"><em><span>Dominic McAfee, Maria Vozzo, and Vivian Cumbo do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Oysters aren’t just good for a feed. They also give a vital boost to coastal ecosystems, which is why efforts are underway to restore Australia’s once-abundant oyster reefs to their former glory.Dominic McAfee, Postdoctoral researcher, marine ecology, University of AdelaideIan McLeod, Senior Research Scientist - Coastal Restoration, James Cook UniversityMaria Vozzo, PhD in Marine Ecology, Macquarie UniversityVivian Cumbo, Postdoctoral Research, Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/716812017-09-11T00:40:32Z2017-09-11T00:40:32ZA deadly herpes virus is threatening oysters around the world<figure><img src="https://images.theconversation.com/files/176279/original/file-20170629-16069-z9yweh.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Colleen Burge counts oysters on an oyster aquaculture lease in California. </span> <span class="attribution"><a class="source" href="http://imet.umces.edu/cburge/?gallery=california-field-work-2015">Collin Closek</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Oysters, a delicacy eaten on most coastlines of the world, are a multi-billion-dollar industry. They also are intriguing to study from a health perspective. Oysters feed by filtering tiny plankton from the surrounding water, processing <a href="http://www.habitat.noaa.gov/abouthabitat/oysterreefs.html">up to 50 gallons</a> per oyster daily. In doing so, they improve water quality and make their ecosystems healthier. But the water that they grow in can be filled with disease-causing microorganisms that can affect both oysters and humans. </p>
<p>Today a deadly herpes virus, <a href="http://dx.doi.org/10.1099/vir.0.80382-0">Ostreid herpesvirus 1 (OsHV-1)</a>, is threatening Pacific oysters (<em>Crassostrea gigas</em>), the world’s most popular and valuable oyster species. It is almost certain to spread more widely in our globally connected world. </p>
<p>I know what you’re thinking: “Oysters get herpes??” Yes, and they can also can get sick from other types of pathogens and stresses. But you won’t contract this virus from eating an oyster, whether you enjoy them on the half-shell or cooked. OsHV-1 can infect other bivalve species, like some animal herpes viruses that <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2815145/">can cross species barriers</a>, but it is genetically distinct from other animal herpes viruses and does not infect humans.</p>
<p>With support from the <a href="http://seagrant.noaa.gov/WhatWeDo/CurrentFocusAreas/SustainableFisheriesandAquaculture.aspx">NOAA Sea Grant aquaculture program</a>, I’m working with a diverse team that includes researchers, regulators and outreach specialists in the United States and abroad to better prepare the U.S. oyster industry for the spread of this virus.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185175/original/file-20170907-9573-19vm7lm.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Dead Pacific oyster sampled during a OsHV-1 mortality event this summer in Tomales Bay, California.</span>
<span class="attribution"><span class="source">Colleen Burge</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Deadly and spreading</h2>
<p>Pacific oysters are native to Asia and are the most popular and valued oyster for aquaculture globally. Humans transferred them from their native range to multiple grow-out areas <a href="http://www.fao.org/fishery/culturedspecies/Crassostrea_gigas/en">globally</a>, including France, the United States and Australia. They are the primary species grown on the U.S. West Coast, whereas both wild and cultured Eastern oysters grow on the East and Gulf coasts. In contrast to Eastern oysters, Pacific oysters were relatively resistant to infectious diseases until OsHV-1 emerged in the early 1990s. </p>
<p>Herpes is often fatal to Pacific oysters. That’s especially true for OsHV-1 microvariants – mutant variants of OsHV-1 which are more virulent than the original reference strain. These viruses are <a href="http://dx.doi.org/10.1098/rstb.2015.0213">spreading globally</a>, causing mass mortalities of Pacific oysters. </p>
<p>An OsHV-1 microvariant was first detected in France in 2008, where it <a href="http://dx.doi.org/10.1016/j.virusres.2010.07.011">killed 80 to 100 percent</a> of affected oyster beds. Since then, similar variants have caused mass mortalities of oysters in many <a href="https://doi.org/10.1007/s10499-015-9919-2">European countries</a>. A 2010 outbreak in England killed <a href="https://www.theguardian.com/environment/2010/jul/23/virus-kent-oysters">over eight million oysters</a>.</p>
<p>OsHV-1 microvariants also infect Pacific oysters in New Zealand and Australia. Their spread in Australia, in particular to Tasmania, has <a href="http://www.abc.net.au/news/2016-02-12/the-human-toll-behind-a-deadly-oyster-disease/7164712">crippled the Australian Pacific oyster aquaculture industry</a>. </p>
<h2>Resistance is the best defense</h2>
<p>U.S. oyster growers are strongly concerned about the spread of OsHV-1 microvariants globally. I was part of the team that first detected OsHV-1 in <a href="http://www.int-res.com/articles/dao2005/63/d063p033.pdf">Tomales Bay, California</a>. To date the virus has been detected only in oysters in Tomales Bay and an adjacent bay, and no microvariants have been found yet in U.S. waters. The California OsHV-1 <a href="http://www.int-res.com/articles/dao2006/72/d072p031.pdf">causes mortalities of young Pacific oysters</a>, but is thought to be less virulent than OsHV-1 microvariants.</p>
<p>Given the spread of the OsHV-1 microvariants elsewhere around the world, it may only be a matter of time until they reach U.S. coastal bays or other nonimpacted oyster growing areas. We spent the summer of 2017 conducting experiments in Tomales Bay to determine whether any cultured U.S. oysters species are resistant to OsHV-1, and soon will also conduct laboratory challenges with OsHV-1 microvariants. </p>
<p>Once OsHV-1 is established within a bay, mass oyster deaths typically occur each year during the summer when water temperatures are warm. The situation is analogous to a human who is infected with herpes and periodically get cold sores. Normally the virus is latent (present at a low level) and does not cause cold sores. But after a stressful situation, the virus replicates and cold sores emerge. </p>
<p>Not all oysters die of herpes, and if OsHV-1 behaves like other herpes viruses, it probably remains present latently within infected oysters’ tissues and is reactivated after a stressful event. For oysters, most of the evidence for virus reactivation points to warm summer water conditions.</p>
<figure>
<iframe src="https://player.vimeo.com/video/99091657" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">Genetic improvements through breeding can improve Pacific oyster survival rates against the OsHV-1 virus.</span></figcaption>
</figure>
<h2>Cultivating oyster resistance</h2>
<p>We can’t vaccinate oysters, and even if antibiotics were effective against viruses, they are not permitted for treating oysters in the United States. Though oysters have an innate immune system that destroys foreign invaders, it lacks an adaptive response, including cells that “remember,” recognize and destroy specific pathogens, as human B or T lymphocytes do. Most vaccines rely on this “immune memory” to be effective. Recent research indicates that oysters’ innate immune systems <a href="https://doi.org/10.1016/j.molimm.2016.09.002">can be stimulated by a virus mimic</a>, but we do not know whether this effect is long-lasting. </p>
<p>The most effective strategy to date has been developing <a href="https://doi.org/10.1016/j.jip.2015.05.010">disease-resistant oyster lines</a>, which can limit both mortalities and oysters’ susceptibility to infection. But this approach involves exposing healthy oysters to the virus – and moving oysters infected with OsHV-1 to naive (disease-free) areas could spread the virus. This means that we can use this approach only in places where OsHV-1 already exists.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/185177/original/file-20170907-9585-34vlai.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185177/original/file-20170907-9585-34vlai.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/185177/original/file-20170907-9585-34vlai.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185177/original/file-20170907-9585-34vlai.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185177/original/file-20170907-9585-34vlai.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185177/original/file-20170907-9585-34vlai.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185177/original/file-20170907-9585-34vlai.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185177/original/file-20170907-9585-34vlai.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pacific oyster seed ready for planting in Tomales Bay, California.</span>
<span class="attribution"><span class="source">Colleen Burge</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Toward that end, breeding programs in locations including France, New Zealand and Australia are working to develop OsHV-1-resistant Pacific oysters. A complementary approach is to expose oysters and determine genes involved in OsHV-1 resistance. I am currently working with two strains of OsHV-1 – the California virus and a microvariant in France – to determine OsHV-1 resistance genes, including a collaboration with the <a href="https://wwz.ifremer.fr/en/">Ifremer</a> station in La Tremblade, France.</p>
<p>The most effective way to limit damage in new locations from OsHV-1 is to limit its spread. However, we also want to be ready in case OsHV-1 microvariants spread to the United States. Beyond their cash value and the benefits that oysters provide by filtering water, <a href="http://www.habitat.noaa.gov/pdf/value_of_oysters.pdf">oyster reefs provide food and habitat</a> for many commercial fish species. Oysters can’t move themselves out of harm’s way, nor can we move all susceptible oysters, so we need to protect them where they grow.</p><img src="https://counter.theconversation.com/content/71681/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Colleen Burge is currently funded by the NOAA Sea Grant Aquaculture Program and the UMBC-UMB Research and Innovation Partnership Grant Program for her work on OsHV-1. She has been funded in the past by California Sea Grant College Program and National Sea Grant.</span></em></p>Oysters grow in seawater and filter their food from it, so how do you shield them from waterborne diseases? Scientists are working to develop strains that are resistant to a fast-spreading herpes virus.Colleen Burge, Assistant Professor, Institute of Marine and Environmental Technology, University of Maryland, Baltimore CountyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/774052017-06-27T20:06:50Z2017-06-27T20:06:50ZHuge restored reef aims to bring South Australia’s oysters back from the brink<figure><img src="https://images.theconversation.com/files/172759/original/file-20170607-29563-agdn8h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mud oysters played a largely unappreciated part in Australia's history.</span> <span class="attribution"><span class="source">Cayne Layton</span>, <span class="license">Author provided</span></span></figcaption></figure><p>The largest oyster reef restoration project outside the United States is underway in the coastal waters of Gulf St Vincent, near Ardrossan in South Australia. Construction began earlier this month. Some 18,000 tonnes of limestone and 7 million baby oysters are set to provide the initial foundations for a 20-hectare reef. </p>
<p>The A$4.2-million project will be built in two phases and should be complete by December 2018. The first phase is the 4-hectare trial currently being built by <a href="http://www.pir.sa.gov.au/">Primary Industries and Regions South Australia</a>; the second phase will see the reef expand to 20 hectares, led by <a href="http://www.natureaustralia.org.au/">The Nature Conservancy</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/175501/original/file-20170625-13435-owjhcq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Some of the 18,000 tonnes of limestone destined for the seafloor.</span>
<span class="attribution"><span class="source">D. McAfee</span></span>
</figcaption>
</figure>
<p>Just 200 years ago the native mud oyster, <em>Ostrea angasi</em>, formed extensive reefs in the Gulf, along more than 1,500km of South Australia’s coastline. Today there are no substantial accumulations of mud oysters anywhere around mainland Australia, with just <a href="http://www.abc.net.au/news/rural/2016-01-06/angasi-oyster-reef-research-restoration/7068628">one healthy reef remaining in Tasmania</a>. </p>
<p>This restoration project aims to pull our native mud oyster back from the brink of extinction in the wild, and restore a forgotten ecosystem that once teemed with marine life.</p>
<h2>More than just seafood</h2>
<p>Oysters played a large role in Australia’s colonial history. When European settlers first arrived they had to navigate a patchwork of oyster reefs (also called <a href="https://www.shellfishrestoration.org.au/">shellfish reefs</a>) that filled the shallow waters of our temperate bays. These enormous structures could cover 10 hectares in a single patch, providing an easily exploited food resource for the struggling early settlers. Oyster shell was burned to produce lime, and the colony’s first buildings were built with the help of oyster cement. </p>
<p>Collectively, these pre-colonial oyster reefs would have rivalled the geographic extent of the Great Barrier Reef, covering thousands of kilometres of Australia’s eastern and southern coastlines.</p>
<p>The history goes back much further too. For thousands of years oyster reefs fed and fuelled trade among Aboriginal communities. Shell middens <a href="http://www.tandfonline.com/doi/abs/10.1080/08920750601169618">dating back 2,000 years</a> attest to the cultural importance of oysters for coastal communities, who ate them in abundance and used their shells to fashion fishhooks and cutting tools. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/175502/original/file-20170625-13435-a2knm0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Health oyster reef in Tasmania.</span>
<span class="attribution"><span class="source">C. Gillies</span></span>
</figcaption>
</figure>
<p>The insatiable appetite of the newly settled Europeans for this bountiful resource was devastating. Not only were live oysters harvested for food, but the dead shell foundations that are critical for the settlement of new oysters were scraped from the seabed for lime burning. Armed with bottom-dredges a wave of exploitation spread across the coast, first overexploiting oyster reefs <a href="http://www.pnas.org/content/101/35/13096.short">close to major urban centres and then further afield</a>. The combination of the lost hard shell bed and increased sediment runoff from the rapidly altered coastal landscape saw oyster populations crash within a century of colonisation.</p>
<p>Today oyster populations are at <a href="http://www.bioone.org/doi/abs/10.1525/bio.2011.61.2.5">less than 1% of their pre-colonial extent</a> in Australia. This is not a unique story – globally it is estimated that <a href="http://www.bioone.org/doi/abs/10.1525/bio.2011.61.2.5">85% of oyster habitat has been lost</a> in the past few centuries, making it one of the most exploited marine habitats in the world. </p>
<p>Today, across much of Australia’s east coast you will see <a href="http://onlinelibrary.wiley.com/doi/10.1890/15-0651/full">Sydney rock oysters</a> encrusting rocky shores, creating a thin veneer around the edge of our bays and estuaries. On the south coast you occasionally see a solitary mud oyster clinging to a jetty pylon. Many Australians don’t realise that this familiar sight represents a mere shadow of the incredible and <a href="http://onlinelibrary.wiley.com/doi/10.1111/cobi.12452/abstract">largely forgotten</a> ecosystems that oysters once supported.</p>
<p>Oysters are an <a href="https://academic.oup.com/bioscience/article/62/10/900/238172/Economic-Valuation-of-Ecosystem-Services-Provided">unsung ecological superhero</a>, with the capacity to increase marine biodiversity, clean coastal waters, enhance neighbouring seagrass, reduce coastal erosion, and even slow the rate of climate change. When oysters cement together, their aggregations form habitat for a great diversity of other invertebrates. A 25cm-square patch of oysters can host more than 1,000 individual invertebrates from a range of different biological groups, in turn providing a smorgasbord for fish. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/175503/original/file-20170625-13993-1g02gf2.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Restoration site, formerly covered with dense oyster habitat.</span>
<span class="attribution"><span class="source">D. McAfee</span></span>
</figcaption>
</figure>
<p>A solitary oyster can <a href="http://darc.cms.udel.edu/ibog/newellecobivalve2.pdf">filter about 100 litres of water a day</a>, which means that <em>en masse</em> they can function as the “kidneys” of our bays, filtering excess nutrients from the water and depositing them on the seafloor. In doing so, they encourage seagrass growth, while their physical structures help to <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0022396">dissipate wave energy</a> and thus reduce the impact of storm surges. </p>
<p>As if all that weren’t enough, oysters are also a <a href="https://academic.oup.com/bioscience/article/62/10/900/238172/Economic-Valuation-of-Ecosystem-Services-Provided">carbon sink</a>, building calcium carbonate shells that are buried in the seafloor after death and eventually compacted to rock, thus helping to prevent carbon dioxide from cycling back into the atmosphere.</p>
<h2>Building it back</h2>
<p>Restoring oyster reefs has the potential to return these ecosystem services and increase the productivity of our coastal ecosystems. The Gulf of St Vincent project came about through an <a href="http://www.environment.sa.gov.au/goodliving/posts/2016/08/artificial-shellfish-reef">election promise by the South Australian Government to boost recreational fishing</a>. A collaboration between <a href="http://www.natureaustralia.org.au/our-work/oceans/restoring-shellfish-reefs/south-australian-reef-to-revive-the-gulf/">The Nature Conservancy</a>, <a href="https://yorke.sa.gov.au/">Yorke Penninsula Council</a> and the <a href="http://pir.sa.gov.au/fishing/community_engagement/habitat_enhancement">South Australian Government</a> will deliver the reef’s foundations, while my colleagues and I at the University of Adelaide are working to ensure that the restored oysters survive and thrive, and that the reef continues to grow.</p>
<p>Hopefully this is just the beginning for large-scale <a href="https://www.shellfishrestoration.org.au/">oyster restoration in Australia</a>, and the lessons learned from this project will guide more restoration projects to improve the health of our oceans. With other restoration projects also underway in <a href="http://www.natureaustralia.org.au/our-work/oceans/restoring-shellfish-reefs/port-phillip-bay/">Victoria</a> and <a href="http://www.natureaustralia.org.au/2016/12/oyster-reefs-back-to-oyster-harbour/">Western Australia</a>, the tide is hopefully turning for our once numerous oysters.</p><img src="https://counter.theconversation.com/content/77405/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sean Connell receives funding from The Ian Potter Foundation and Department of Environment Water and Natural Resources and The Environment Institute of The University of Adelaide for this research. </span></em></p><p class="fine-print"><em><span>Dominic McAfee does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>In colonial times Australia’s waters were teeming with mud oysters that provided food, cement, and cleaned the oceans. Now a 20-hectare man-made reef aims to restore some of their former glory.Dominic McAfee, Postdoctoral researcher, marine ecology, University of AdelaideSean Connell, Professor, Ecology, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/549762016-02-18T18:45:20Z2016-02-18T18:45:20ZMussel power: how ocean acidification is changing shells<figure><img src="https://images.theconversation.com/files/111960/original/image-20160218-1236-mitene.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The mussel hustle</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=blue%20mussel&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=1395222">Joy Prescott</a></span></figcaption></figure><p>One of the big problems with the world’s heavy carbon emissions is that they are driving up the levels of carbon dioxide in our oceans, which is making them more acidic. The surface pH of the oceans <a href="http://www.ipcc.ch/pdf/assessment-report/ar5/syr/AR5_SYR_FINAL_SPM.pdf">has already</a> dropped from 8.1 to 8.0 over the past couple of decades, and is projected to reach 7.7 by 2100 – a huge change in biological terms. </p>
<p>This is reducing the carbonate in the water that marine organisms including shellfish, corals and sea urchins depend on to make their shells and exoskeletons. I co-published <a href="http://rsif.royalsocietypublishing.org/content/12/103/20141227">a study</a> two years ago into how this would affect mussels. By simulating the ocean conditions of 2100, we found that their shells did not grow as large and were harder and more brittle. Now, in a <a href="http://www.nature.com/articles/srep21076">new study</a>, we have seen fascinating signs of them adapting to these changes. </p>
<p>When we looked at the mussel shells of the future in our first study, we found they fractured considerably more easily. This made them more vulnerable to predators such as birds and crabs – and also to stormy conditions, since the stronger waves can bang them against rocks and other mussels. As an economically important food source across the world, it has worrying implications for those who depend on them to make their living – indeed, mussel farmers tell me they are noticing these changes even now. It also raises the prospect of similar problems for other shellfish such as oysters and cockles, not to mention sea urchins and corals.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/111993/original/image-20160218-12817-cw28iz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/111993/original/image-20160218-12817-cw28iz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/111993/original/image-20160218-12817-cw28iz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/111993/original/image-20160218-12817-cw28iz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/111993/original/image-20160218-12817-cw28iz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/111993/original/image-20160218-12817-cw28iz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/111993/original/image-20160218-12817-cw28iz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/111993/original/image-20160218-12817-cw28iz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Coral grief?</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=coral&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=287417138">John_Walker</a></span>
</figcaption>
</figure>
<h2>Adaptation</h2>
<p>Our <a href="http://www.nature.com/articles/srep21076">new study</a> took the work further by using a combination of X-ray techniques to understand how ocean acidification causes these changes and how the organisms continue to make their shells in spite of it. </p>
<p>Marine organisms such as mussels create shells in several stages. They take up the carbonates and calcium in sea water through their tissue and convert them into a substance known as amorphous calcium carbonate (ACC). They essentially move this substance to the correct location in their body and convert it into a harder substance called crystalline calcium carbonate (CCC), which comprises the bulk of the shell. But they also keep some carbonate in ACC form, which they use for repair purposes – not unlike the way humans grow bones. </p>
<p>Our “future mussels” had to cope with the uptake of fewer carbonates overall, but what they did was to convert a lower proportion into CCC than usual – hence they grew less shell. Instead they kept more as ACC, which seemed to be a repair mechanism to combat the increased risk of shell damage from having more brittle shells. </p>
<p>So is this a sign that nature will find a way to cope as the oceans get more acidic? Not necessarily. The mussels might have been retaining more of the repairing ACC, but they are vulnerable while the shell is fractured, and might not live long enough to fix it. </p>
<p>We also don’t yet know whether they would have enough ACC to keep their more brittle shells in a good enough state of repair. To find out, you would have to look at what happens to them over a number of generations. This is what we intend to look into next. This research will have huge implications for other marine organisms producing calcium carbonate shells and exoskeletons including shellfish, corals and sea urchins. In the meantime, ocean acidification undoubtedly means huge changes for the creatures that live there, with consequences that are extremely difficult to predict.</p><img src="https://counter.theconversation.com/content/54976/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Susan Fitzer's work on mussels received funding from the Leverhulme Trust</span></em></p>Shellfish will have more brittle shells as oceans get more acidic – making them more vulnerable to predators. New research gives a fascinating glimpse into how they will adapt.Susan Fitzer, Research Assistant, University of GlasgowLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/45882012-01-09T02:46:57Z2012-01-09T02:46:57ZMonday’s medical myth: eating oysters makes you randy<figure><img src="https://images.theconversation.com/files/6815/original/r97s93zt-1326076934.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Oysters can still play an important role in romance, even though they aren’t an aphrodisiac.</span> <span class="attribution"><span class="source">Stephen Coles</span></span></figcaption></figure><p><strong>The stuff of romance novels or a secret tool to give you a boost in the bedroom? We start the year by examining the truth about oysters.</strong></p>
<p><em>Holly gazed around in awe. Rory had brought her to a tiny waterfront restaurant. From the table on the jetty she watched the setting sun sparkle across the bay and reflect off Rory’s chocolate brown eyes.</em> </p>
<p><em>“I hope you like oysters, Holly. I took the liberty of ordering us three dozen with samples of the chef’s special toppings. This restaurant is famous for their delicious oysters.”</em></p>
<p><em>Holly sighed. Although she had known Rory for a while, this was their first date and very romantic. “Remember, first date, home alone by midnight,” she murmured, more as a reminder to herself. But, oysters! Heavens, weren’t they supposed to be an aphrodisiac?</em></p>
<p>Does Holly withstand the oyster’s reputation for inspiring passion? Or will they make her abandon caution and leap into Rory’s embrace? </p>
<p>All will be revealed – but first a short aside.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/6803/original/nrqc5ntb-1326071969.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/6803/original/nrqc5ntb-1326071969.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/6803/original/nrqc5ntb-1326071969.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/6803/original/nrqc5ntb-1326071969.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/6803/original/nrqc5ntb-1326071969.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/6803/original/nrqc5ntb-1326071969.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/6803/original/nrqc5ntb-1326071969.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Lee & Chantelle McArthur</span></span>
</figcaption>
</figure>
<p>Like all good myths, there’s an element of truth in the “oysters-make-you-randy” story. But a plateful of oysters for dinner will not, by themselves, lead to a night of wild passion. </p>
<p>Having said that, back in 2005, newspapers in <a href="http://www.telegraph.co.uk/news/uknews/1486054/Raw-oysters-really-are-aphrodisiacs-say-scientists-and-now-is-the-time-to-eat-them.html">the United Kingdom</a> and in <a href="http://www.smh.com.au/articles/2005/03/23/1111525227607.html">Australia</a> reported with breathless glee that scientists had finally made a connection between eating oysters and a rise in the levels of sex hormones in male and female rats due to the existence of a couple of unusual amino acids. </p>
<p>Perhaps Casanova was right to power up with oysters before his lusty bedroom activities. He went through <a href="http://www.cuanoysters.com/true/index.html">60 of the slippery molluscs</a> a day, which would have had a beneficial impact on his body’s zinc level, never mind his sex hormones.</p>
<p>Oysters are a particularly good source of zinc, an important mineral in our diet and essential for function of many of our body’s systems. A shortage of zinc can have a <a href="http://journals.lww.com/co-gastroenterology/Abstract/2009/03000/Zinc_deficiency.9.aspx">detrimental effect</a> on our reproductive systems, and the mineral is also known to help boost testosterone levels. </p>
<p>We don’t store zinc in our bodies so we have to replenish the supply regularly. Zinc from fish and meat is better absorbed by our bodies than zinc in grains. Liver has a good supply of zinc – think paté and this option becomes sexier – but oysters have a whole lot more of the mineral than <a href="http://www.mja.com.au/public/nutrition/women/wquest3.html">any red meat</a>.</p>
<p>But when did we start eating oysters? There’s evidence from middens found around the Australian coast that Aboriginal communities were eating oysters some <a href="http://www.dpcd.vic.gov.au/__data/assets/pdf_file/0011/35894/AA_13_ShellMiddens_13.06.08.pdf">12,000</a> to <a href="http://www.environment.gov.au/parks/booderee/culture-history/aboriginal-history.html">20,000</a> years ago. </p>
<p>In more recent times, <a href="http://www.jstor.org/pss/3293643">the Romans</a> considered oysters as a delicacy. Pliny wrote that the best oysters were found in river mouths where light from the sun made them sweet and plump. </p>
<p>So fond were the Romans of oysters that they even developed ways to cultivate them, creating the first oyster farms. And when they invaded Britain, the Romans discovered a plentiful supply of oysters around Britain’s coast; oysters that were shipped back to Rome live for the discerning Roman public. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/6800/original/jrp8sw4q-1326071420.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/6800/original/jrp8sw4q-1326071420.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/6800/original/jrp8sw4q-1326071420.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/6800/original/jrp8sw4q-1326071420.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/6800/original/jrp8sw4q-1326071420.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/6800/original/jrp8sw4q-1326071420.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/6800/original/jrp8sw4q-1326071420.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The demise of oyster beds means what we eat now are farmed.</span>
<span class="attribution"><span class="source">Durundal</span></span>
</figcaption>
</figure>
<p>By the 18th century, oysters had become an easily accessible food for <a href="http://gothamcenter.org/blotter/?p=66">New York</a> and London poor. They were dredged by fishermen in barges, or picked over by hand at low tide, and sold by <a href="http://www.oldbaileyonline.org/static/London-life.jsp">street sellers</a> pushing barrows. But by the <a href="http://h2g2.com/dna/h2g2/classic/A283105">middle of the 19th century</a>, the oyster beds were gone – destroyed through indiscriminate fishing practices. </p>
<p>As availability of oysters decreased, cultivated oysters became an extravagance and were sold at a premium price. With the demise of the oyster beds went the <a href="http://www.thefishsite.com/articles/696/cracking-the-demise-of-oysters">natural filtration processes</a> that kept waters clear, an increasingly urgent problem <a href="http://www.bbc.co.uk/blogs/thereporters/richardblack/2011/02/this_week_saw_formal_scientifi.html">recognised today</a>. </p>
<p>Here in Australia, we have three main types of farmed oysters: the Sydney rock oyster and the Angasi oyster are native to Australia, while the Pacific oyster is a native of Japan. The majority of our oysters are farmed in New South Wales, Tasmania and South Australia and we enjoy them so much that <a href="http://www.oystersaustralia.org.au/">only 3% is exported</a>. </p>
<p>Oysters may not make you randy but they do contribute to a healthy diet, which is definitely a good way to maintain sexual health. And don’t forget the pure sensual pleasure of eating oysters. The slippery, salty creature cupped in its own misshapen shell, bathed in brine, topped with a splash of lemon, a shalloty vinegar reduction or a citrusy ponzu dressing – just orgasmic!</p>
<p>So if you’re taking your partner to dinner and want to set the mood, don’t abandon the oysters… or the location, the champagne and the candlelight. Oysters can still play an important role in the game of romance, even though they aren’t an aphrodisiac in a shell.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/6805/original/2ggq9qbm-1326072312.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/6805/original/2ggq9qbm-1326072312.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/6805/original/2ggq9qbm-1326072312.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/6805/original/2ggq9qbm-1326072312.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/6805/original/2ggq9qbm-1326072312.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/6805/original/2ggq9qbm-1326072312.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/6805/original/2ggq9qbm-1326072312.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">There’s more than one food that leads to your lover’s heart.</span>
<span class="attribution"><span class="source">Premshree Pillai</span></span>
</figcaption>
</figure>
<p>And so, back to our story…</p>
<p><em>Holly woke to find Rory gone. Self-recrimination hung like a shadow in the daylight. Eating those oysters, what was she thinking?</em></p>
<p><em>“Are you awake, Holly, gorgeous girl?” Rory stood in the doorway holding a breakfast tray in his hands. “Breakfast delivered to your bedside, princess. Cafe au lait and the best pain au chocolat in the whole town.”</em></p>
<p><em>Hastily flattening her tousled hair, Holly sat up, sniffing the glorious aromas of steaming coffee and buttery croissants. She gazed hungrily at the curls of chocolate oozing from the crisp pastry.</em></p>
<p><em>“Rory … how wonderful!” grinned Holly, feeling overwhelmingly happy.</em></p>
<p><em>Rory gave Holly a wicked smile, “They say oysters are an aphrodisiac but wait til you eat the chocolate. Nothing beats chocolate for arousing passion.”</em></p><img src="https://counter.theconversation.com/content/4588/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Penny Wilson does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The stuff of romance novels or a secret tool to give you a boost in the bedroom? We start the year by examining the truth about oysters. Holly gazed around in awe. Rory had brought her to a tiny waterfront…Penny Wilson, PhD Researcher, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.